Assessment of the characteristics of a particular charger is difficult without an understanding of how the exemplary charge Li-ion battery should actually flow. Therefore, before proceeding directly to the schemes, let's remember the theory a little.

What are lithium batteries

Depending on which material is made of a positive lithium battery electrode, there are several varieties:

• with cobeda of cobaltat lithium;
• with cathode based on lithium iron phosphate;
• based on nickel-cobalt aluminum;
• based on nickel-cobalt-manganese.

All these batteries have their own characteristics, but since for a wide consumer, these nuances have no fundamental importance, in this article they will not be considered.

All Li-Ion batteries are also produced in various sizes and form factors. They can be both in a housing design (for example, 18650 popular today) and in laminated or prismatic design (gel polymer batteries). The latter are hermetically sealed packages made of special films in which electrodes and electrode mass are located.

The most common sizes of Li-Ion batteries are shown in the table below (they all have a rated voltage of 3.7 volts):

Designation	Size	Similar sizes
Xxyy0., Where XX - indication of the diameter in mm, Yy - value of length in mm, 0 - reflects the execution in the form of a cylinder	10180	2/5 AAA.
	10220	1/2 AAA (Ø corresponds to AAA, but half of the length)
	10280
	10430	AAA
	10440	AAA
	14250	1/2 AA
	14270	Ø AA, length CR2
	14430	Ø 14 mm (like AA), but length is less
	14500	AA
	14670
	15266, 15270	CR2.
	16340	CR123.
	17500	150s / 300s.
	17670	2xCr123 (or 168S / 600S)
	18350
	18490
	18500	2xcr123 (or 150a / 300p)
	18650	2xcr123 (or 168a / 600p)
	18700
	22650
	25500
	26500	FROM
	26650
	32650
	33600	D.
	42120

Internal electrochemical processes proceed equally and do not depend on the form factor and the execution of the AKB, so everything that has been said is equally applied to all lithium batteries.

How to charge lithium-ion batteries

The most correct way of charge lithium batteries is charged in two stages. This method uses Sony in all its chargers. Despite the more complex charge controller, it provides a more complete charge of Li-Ion batteries, without reducing their service life.

Here we are talking about a two-step charge profile of lithium batteries, shortcutly referred to as CC / CV (Constant Current, Constant Voltage). There are still options with hypertices and speed currents, but in this article they are not considered. Read more about charging pulse current you can read.

So, consider both stages of charge.

1. At the first stage A constant charge current must be provided. The value of the current is 0.2-0.5c. For an accelerated charge, an increase in current is allowed to 0.5-1.0 ° C (where C is the battery capacity).

For example, for a battery with a capacity of 3000 m / h, the rated charge current at the first stage is 600-1500 mA, and the current charge current may lie within 1.5-3A.

To ensure permanent charging current of a given value, the charger diagram (memory) should be able to raise the voltage on the battery terminals. In fact, at the first stage, it works as a classic current stabilizer.

Important: If you plan batteries with an integrated protection board (PCB), then when designing a memory circuit, you must make sure that the idling stroke voltage will never be able to exceed 6-7 volts. Otherwise, the protection board may fail.

At a time when the voltage on the battery rises to the value of 4.2 volts, the battery drops approximately 70-80% of its capacitance (the specific value of the capacity will depend on the charge current: with an accelerated charge it will be slightly smaller, at a nominal one - a little more). This moment is the end of the first stage of the charge and serves as a signal to move to the second (and last) stage.

2. The second stage of charge - This is a battery charge by constant voltage, but gradually decreased (falling) current.

At this stage, the voltage 4.15-4.25 voltage maintains on the battery and controls the current value.

As the tank set, the charging current will decrease. As soon as its value decreases to 0.05-0.01С, the charge process is considered to be completed.

An important nuance of the proper charger is its complete shutdown from the battery after the end of charging. This is due to the fact that for lithium batteries is extremely undesirable to their long-term detection under increased voltage, which usually provides memory (i.e. 4.18-4.24 volts). This leads to accelerated degradation of the chemical composition of the battery and, as a result, reducing its capacity. Under long finding is meant tens of hours or more.

During the second stage of charge, the battery has time to score more than about 0.1-0.15 of its capacitance. The overall charge of the battery thus reaches 90-95%, which is an excellent indicator.

We looked at the two main stages of charge. However, the coverage of the charge of lithium batteries would be incomplete if another charge stage was not mentioned - so-called. Prepare.

Preliminary Charge Stage (Prepare) - This stage is used only for deeply discharged batteries (below 2.5 V) to output them to normal operational mode.

At this stage, the charge is provided with a constant current of the reduced value until the voltage on the battery reaches 2.8 V.

The preliminary stage is necessary to prevent intimidation and depressurization (or even an explosion with fire) damaged batteries having, for example, internal short circuit between the electrodes. If through such a battery immediately skip a high charge current, it will inevitably lead to healing it, and then how lucky.

Another benefit of the prerequisite is pre-warming the battery, which is relevant when charging at low ambient temperatures (in the unheated room during the cold season).

Intelligent charging should be able to control the voltage on the battery during the preliminary stage of the charge and, if the voltage does not rise long time, make an output of the battery malfunction.

All stages of charge lithium-ion battery (including the prerequisite stage) are schematically depicted on this schedule:

Excess of the nominal charging voltage by 0.15V can reduce battery life twice. A decrease in the charge voltage by 0.1 volts reduces the capacity of the charged battery by about 10%, but significantly extends its service life. The voltage of the fully charged battery after removing it from the charger is 4.1-4.15 volts.

Summarize the above, we denote the basic theses:

1. What is the current to charge the Li-Ion battery (for example, 18650 or any other)?

The current will depend on how quickly you would like to charge it and can lie in the range from 0.2c to 1C.

For example, for a battery size of 18650 with a capacity of 3400 mA / h, the minimum charge current is 680 mA, and the maximum - 3400 mA.

2. How much time needs to be charged, for example, the same accumulatory batteries 18650?

The charge time directly depends on the charge current and is calculated by the formula:

T \u003d C / I ZA.

For example, the charge time of our accumulator with a capacity of 3400 mA / h current in 1a will be about 3.5 hours.

3. How to charge a lithium-polymer battery correctly?

Any lithium batteries charge the same. It does not matter, lithium-polymer he or lithium-ion. For us, consumers, there is no difference.

What is the protection board?

The protection board (or PCB - POWER Control Board) is designed to protect against short circuit, reloading and redevelopment of a lithium battery. As a rule, overheating protection is also built into the protection modules.

In order to comply with safety, the use of lithium batteries in household appliances is prohibited if the protection fee is not built into them. Therefore, in all batteries from cell phones there is always a PCB fee. Output terminals of the battery are placed right on the board:

These boards use a six-legged charge controller on a specialized microme (JW01, JW11, K091, G2J, G3J, S8210, S8261, NE57600, etc. Analogs). The task of this controller is to disconnect the battery from the load when the battery is fully discharged and shutting down the battery from charging upon reaching 4.25V.

Here, for example, a BP-6M battery protection circuit, which supplied old Nokiev phone phones:

If we talk about 18650, they can be released as a protection fee so without it. The protection module is located in the area of \u200b\u200bthe minus battery terminal.

The board increases the battery length by 2-3 mm.

Batteries without a PCB module are usually included in batteries completed with their own protection schemes.

Any battery with protection is easily turning into a battery without protection, just just jump it.

To date, the maximum capacity of the accumulator 18650 is 3400 mA / h. Batteries with protection necessarily have a corresponding designation on the housing ("Protected").

Do not confuse PCB fee with PCM module (PCM - Power Charge Module). If the first serve only the targets for protecting the battery, then the second are designed to control the charge process - limit the charge current at a given level, control the temperature and, in general, ensure the entire process. The PCM board is what we call the charge controller.

I hope now there are no questions left, how to charge a 18650 battery or any other lithium? Then we turn to a small selection of ready-made schematic solutions of chargers (those most charge controllers).

Battery Li-Ion Charge Schemes

All schemes are suitable for charging any lithium battery, it remains only to determine the charging current and an element base.

LM317.

Scheme of a simple charger based on the LM317 chip with charge indicator:

The simplest scheme, the entire setting is reduced to the installation of the output voltage of 4.2 volts using the R8 stroke resistor (without a connected battery!) And the charge current installation by selecting resistors R4, R6. The power of the resistor R1 is at least 1 watt.

As soon as the LED goes out, the charge process can be finished (the charging current to zero will never decrease). It is not recommended to keep the battery in this charging for a long time after it is fully charged.

The LM317 microcircuit is widely used in various voltage and current stabilizers (depending on the inclusion circuit). Sold on every corner and stands at all a penny (you can take 10 pcs. Total for only 55 rubles).

LM317 happens in different buildings:

Purpose of conclusions (Cocolevka):

Analogues of the LM317 chip are: GL317, SG31, SG317, UC317T, ECG1900, LM31MDT, SP900, KR142EN12, KR1157EN1 (last two - domestic production).

Charging current can be increased to 3A if instead of LM317 take LM350. She, however, will be more expensive - 11 rubles / pcs.

The printed circuit board and the collection scheme are shown below:

The old Soviet CT361 transistor can be replaced by a similar P-N-P transistor (for example, KT3107, Kt3108 or Bourgeois 2N5086, 2SA733, BC308A). It can be removed at all if the charge indicator is not needed.

Lack of scheme: supply voltage must be within 8-12V. This is due to the fact that for normal operation of the LM317 chip, the difference between the battery voltage and the supply voltage should be at least 4.25 volts. Thus, the USB port will not be powered.

MAX1555 or MAX1551

MAX1551 / MAX1555 - specialized chargers for Li + batteries that can work from USB or from a separate power adapter (for example, a charger from the phone).

The only difference between these chips - max1555 gives a signal for the charge indicator, and MAX1551 is the signal that power is enabled. Those. 1555 In most cases, it is still preferable, so 1551 is already difficult to find on sale.

Detailed description of these chips from the manufacturer.

The maximum input voltage from the DC adapter is 7 V, when powered by USB - 6 V. When a supply voltage is reduced to 3.52 V, the chip is disconnected and the charge stops.

The microcircuit itself detects at what input is the supply voltage and connects to it. If the power goes according to the USB bus, the maximum charge current is limited to 100 mA - it allows you to push the charger to the USB port of any computer without fear of burning the southern bridge.

When powered from a separate power supply, the typical value of the charging current is 280 mA.

In the microcircuits are built-in overheating protection. But even in this case, the scheme continues to operate, reducing the charge current by 17 mA per degree above 110 ° C.

There is a pre-charge function (see above): until the voltage on the battery is below 3V, the chip limits the charge current at 40 mA.

The microcircuit has 5 conclusions. Here is a typical inclusion scheme:

If there is a guarantee that at the output of your adapter, the voltage must not be able to exceed 7 volts, then you can do without a 7805 stabilizer.

USB charging option can be collected, for example, on such.

The chip does not need external diodes, nor in external transistors. In general, of course, gorgeous microhi! Only they are small too, to solder uncomfortable. And still cost ().

LP2951

The LP2951 stabilizer is made by National Semiconductors (). It provides the implementation of the built-in current limit function and allows you to form a stable level of charge voltage level of a lithium-ion battery at the output scheme.

The value of the charge voltage is 4.08 - 4.26 volts and is set to the R3 resistor when the battery is disconnected. Voltage is very accurate.

The charge current is 150 - 300mA, this value is limited by the internal circuits of the LP2951 chip (depends on the manufacturer).

Diode apply with low reverse current. For example, it can be any of the 1N400X series, which will be able to purchase. The diode is used as blocking, to prevent the return current from the battery in the LP2951 chip when the input voltage is disconnected.

This charging gives a rather low charging current, so that any battery 18650 can charge all night.

The chip can be bought both in the DIP-housing and in the SOIC housing (cost of about 10 rubles for the face).

MCP73831

The chip allows you to create the right chargers, besides it is cheaper than the promoted MAX1555.

Typical inclusion scheme taken from:

An important advantage of the scheme is the absence of low-level powerful resistors that limit the charge current. Here the current is set by the resistor connected to the 5th conclusion of the chip. Its resistance must lie in the range of 2-10 com.

Charging assembly looks like this:

The microcircuit in the process of work is well heated so much, but it does not seem to her. Performs your function.

Here is another printed circuit board option with the SMD LED and the micro-USB connector:

LTC4054 (STC4054)

Very simple scheme, excellent option! Allows you to charge up to 800 mA (see). True, it has a property very much, but in this case the built-in overheating protection reduces the current.

You can easily simplify the scheme by throwing out one or even both LEDs with a transistor. Then she will look like this (you see, it's easier to nowhere: a pair of resistors and one Conder):

One of the printed circuit board options is available by software. The board is calculated under the elements of the size of 0805.

I \u003d 1000 / R. Immediately a large current is not worth it, first look at how much the microcircuit will be warm. I took the resistor for my goals at 2.7 com, while the charge current turned out about 360 mA.

The radiator to this chip is unlikely to be able to adapt, and not the fact that it will be effective due to the high thermal resistance of the transition of the crystal-housing. The manufacturer recommends making the heat sink "through the conclusions" - to make as thick paths as possible and leave the foil under the chip body. And in general, the more "earth" foil will be left, the better.

By the way, most of the heat is given through the 3rd leg, so you can make this track very wide and thick (pour it with an overpressure of solder).

The LTC4054 chip body may have LTH7 or Ltady marking.

LTH7 from Ltady is distinguished by the fact that the first can raise a strongly sitting battery (on which the voltage is less than 2.9 volts), and the second - no (you need to split separately).

The chip came out very successful, so it has a bunch of analogues: STC4054, MCP73831, TB4054, QX4054, TP4054, SGM4054, ACE4054, LP4054, U4054, BL4054, WPM4054, IT4504, Y1880, PT6102, PT6181, VS6102, HX6001, LC6000, LN5060, CX9058, EC49016, CYT5026, Q7051. Before using any of the analogues, check on datasheets.

TP4056.

The microcircuit is made in the SOP-8 case (see), has a metal heat generator on a belly, which allows you to more effectively remove heat. Allows you to charge the battery to 1a (depends on the current resistor).

The connection scheme requires the minimum of attachments:

The scheme implements the classic charge process - first the charge of a constant current, then a constant voltage and a falling current. Everything is scientifically. If you disassemble charging in steps, you can select several stages:

1. Control of the voltage of the connected battery (this happens constantly).
2. Prerequisite phase (if the battery is discharged below 2.9 V). 1/10 charge from the R PROG programmed by the resistor (100ma at R Prog \u003d 1.2 com) to 2.9 V.
3. Charging with the maximum current of a constant value (1000mA at R Prog \u003d 1.2 com);
4. When it is reached on the battery 4.2 V, the battery voltage is fixed at this level. The smooth decrease in the charging current begins.
5. When the current 1/10 is reached from the R PROG programmed by the resistor (100ma at R Prog \u003d 1.2kom), the charger is turned off.
6. After the charging is completed, the controller continues to monitor the battery voltage (see clause 1). Current consumed by a monitoring scheme 2-3 μA. After the voltage drop to 4.0V, the charging is turned on again. And so in a circle.

Charge current (in amperes) is calculated by the formula I \u003d 1200 / R Prog. The maximum permissible is 1000 mA.

The real charge charge with a battery 18650 by 3400 mA / h is shown in the graph:

The advantage of the chip is that the charge current is given by only one resistor. Most powerful low-level resistors are required. Plus there is an indicator of the charge process, as well as an indication of the end of charging. With an unscheduled battery, the indicator blinks with a frequency once a few seconds.

The supply voltage of the diagram must lie within 4.5 ... 8 volts. The closer to 4.5V, the better (so the chip is heated less).

The first foot is used to connect the temperature sensor built into the lithium-ion battery (usually this is the middle output of the cell phone battery). If the voltage output is below 45% or above 80% of the supply voltage, the charging is suspended. If you do not need control control, just put this leg to the ground.

Attention! This scheme has one significant disadvantage: the lack of a battery reversal protection scheme. In this case, the controller is guaranteed to focus due to exceeding the maximum current. At the same time, the supply voltage of the circuit directly falls on the battery, which is very dangerous.

Printing is simple, it is done per hour on the knee. If the time is tolerate, you can order ready-made modules. Some manufacturers of ready-made modules add protection against overload and overloading (, for example, you can choose which fee you need - with or without protection, and with what connector).

You can also find ready-made boards with an derived contact for the temperature sensor. Or even a charging module with several TP4056 chicircles for increasing the charging current and with a stir protection (example).

LTC1734.

Also a very simple scheme. The charge current is set by the R PROG resistor (for example, if you put a resistor by 3 kΩ, the current will be 500 mA).

Chips usually have labeling on the housing: ltrg (they can often be found in old phones from Samsung).

The transistor is at all suitable for any P-N-P, the main thing is that it is designed for a given charging current.

The charge indicator on the specified scheme is not, but in LTC1734 it is said that the output "4" (PROG) has two functions - the current installation and control of the battery charge. The example shows a scheme with charge end control using the LT1716 comparator.

The LT1716 comparator in this case can be replaced by cheap LM358.

TL431 + transistor

Probably it is difficult to come up with a scheme from more affordable components. It is the most difficult thing here is to find the TL431 reference voltage source. But they are so common that they are found almost everywhere (rarely, as a source of nutrition costs without this chip).

Well, the TIP41 transistor can be replaced with any other with a suitable collector current. Even old Soviet CT819, CT805 (or less powerful KT815, KT817) are suitable.

The scheme setting is reduced to the output voltage setting (without battery !!!) using a stroke resistor at 4.2 volts. Resistor R1 sets the maximum charging current value.

This scheme fully implements a two-step process of charge lithium batteries - first charging a direct current, then the transition to the voltage stabilization phase and the smooth decrease in the current almost to zero. The only drawback is the poor repeatability of the circuit (the caprication in the setting and demanding to the components used).

MCP73812.

There is one more undeservedly deprived of the microcircuit from Microchip - MCP73812 (see). At its base, it turns out a very budget version of charging (and inexpensive!). All body kit is just one resistor!

By the way, the chip is performed in a package convenient for soldering - SOT23-5.

The only minus is greatly heated and there is no charge indication. She is still somehow working very well if you have a low-power supply source (which gives stress drawdown).

In general, if the charge indication is not important for you, and the current of 500 mA suits you, then the MSR73812 is a very good option.

NCP1835

A fully integrated solution is proposed - NCP1835B, providing high stability of the charging voltage (4.2 ± 0.05 V).

Perhaps the only disadvantage of this chip is its too miniature size (DFN-10 case, size 3x3 mm). Not everyone can provide high-quality soldering of such miniature elements.

From indisputable benefits I would like to note the following:

1. The minimum number of body parts.
2. The possibility of charging a fully discharged battery (overhead of the current of 30mA);
3. Determining the end of charging.
4. Programmable charging current - up to 1000 mA.
5. Indication of charge and errors (able to detect unloadable batteries and signal it).
6. Protection against a long charge (changing the capacitor capacitor with T, you can set the maximum charge time from 6.6 to 784 minutes).

The cost of the chip is not so kopeck, but not so big (~ $ 1) to abandon its use. If you are friends with a soldering iron, I would recommend to stop your choice on this option.

More detailed description is in.

Is it possible to charge a lithium-ion battery without a controller?

Yes, you can. However, this will require tight control of the charging current and voltage.

In general, to charge the battery, for example, our 18650 will not work at all without a charger. All the same, it is necessary to somehow limit the maximum charge current, so at least the most primitive memory, but still it will be necessary.

The simplest charger for any lithium battery is a resistor enabled sequentially with the battery:

The resistance and power of the scattering of the resistor depend on the power supply voltage to be used for charging.

Let's calculate the resistor for the power supply of 5 volts. We will charge the 18650 battery, with a capacity of 2400 mA / h.

So at the very beginning of charging drop voltage on the resistor will be:

U r \u003d 5 - 2.8 \u003d 2.2 volts

Suppose our 5-volt power supply is calculated for maximum current 1A. The biggest current scheme will consume at the very beginning of the charge, when the voltage on the battery is minimal and is 2.7-2.8 volts.

ATTENTION: These calculations are not taken into account the likelihood that the battery can be very deeply discharged and the voltage on it can be much lower, right up to zero.

Thus, the resistance of the resistor necessary to limit the current at the very beginning of the charge at the level of 1 amp should be:

R \u003d u / i \u003d 2.2 / 1 \u003d 2.2 ohms

Resistor dispersion capacity:

P r \u003d i 2 r \u003d 1 * 1 * 2.2 \u003d 2.2 W

At the very end of the battery charge, when the voltage on it approaches 4.2 V, the charge current will be:

I \u003d (U IP - 4.2) / R \u003d (5 - 4.2) / 2.2 \u003d 0.3 A

Those., As we see, all values \u200b\u200bdo not go beyond permissible for this battery: the initial current does not exceed the maximum allowable charge current for a given battery (2.4 a), and the final current exceeds the current at which the battery is already stopped recruiting the container ( 0.24 a).

The most important drawback of such charging is to constantly monitor the voltage on the battery. And manually disable the charge as soon as the voltage reaches 4.2 volts. The fact is that lithium batteries are very poorly carrying even short-term overvoltage - the electrode masses begin to degrade rapidly, which inevitably leads to loss of tank. At the same time, all prerequisites for overheating and depressurization are created.

If the protection fee is built into your battery, about which it was slightly higher, then everything is simplified. Upon reaching a certain battery voltage, the board itself turns it off from the charger. However, this method of charging has the essential minuses that we told in.

Protection embedded in the battery will not allow it to recharge under any circumstances. All you have to do is to control the charge current so that it does not exceed the permissible values \u200b\u200bfor this battery (the protection fees do not know how to limit the charge current, unfortunately).

Charging with the Laboratory Power Supply

If your disposal has a power supply with protection (restriction) by current, then you are saved! Such a power source is already a full-fledged charger that implements the correct charge profile, which we wrote above (CC / CV).

All you need to be done to charge Li-Ion is to set 4.2 volts on the power supply and set the desired current limit. And you can connect the battery.

At first, when the battery is still discharged, the laboratory power supply will operate in current protection mode (i.e. will stabilize the output current at a given level). Then, when the tension on the bank rises to the 4.2V installed, the power supply will switch to the voltage stabilization mode, and the current will start falling.

When the current falls to 0.05-0.1c, the battery can be fully charged.

As you can see, laboratory BP is a practically perfect charger! The only thing he does not know how to do automatically, is to make a decision to complete the battery charging and turn off. But this is a trifle, which is not even worth paying attention.

How to charge lithium batteries?

And if we are talking about a disposable battery that is not intended for recharging, the correct (and the only right) answer to this question is in any way.

The fact is that any lithium battery (for example, the common CR2032 in the form of a flat tablet) is characterized by the presence of an internal passivating layer, which is covered with a lithium anode. This layer prevents the chemical reaction of an anode with an electrolyte. A third-party feed destroys the above protective layer, leading to a damage of the battery.

By the way, if we talk about an unloadable CR2032 battery, that is, the LIR2032 very similar to it is already a full battery. Its can be charged. Only she does not voltage 3, but 3.6V.

About the same way to charge lithium batteries (whether there is a phone battery, 18650 or any other Li-Ion battery) was discussed at the beginning of the article.

85 cop / pcs. Buy MCP73812. 65 rub / PC. Buy NCP1835 83 rub / pc. Buy * All microcircuits with free shipping

Stmicroelectronics is a line of ICs intended for building chargers for lithium batteries, consists of just eight products, but these products cover the entire range of market needs in such products. The line includes battery charge chips, battery monitoring chips and the level of its charge level.

In modern mobile electronic devices, even those that are designed with
by consideration of minimizing power consumption, the use of non-established batteries goes into the past. And from an economic point of view - Already in a short time interval, the total cost of the required number of one-time batteries will quickly exceed the cost of one battery, and in terms of user convenience - it's easier to recharge the battery than to search where to buy a new battery. Accordingly, battery chargers become a guaranteed product. It is not surprising that almost all the manufacturers of integrated circuits for power supply devices pay attention to the "charger" direction.

Another five years ago, a discussion of the battery charge microcircuits (Battery Chargers IC) began with a comparison of the main types of batteries - nickel and lithium. But at present, nickel batteries have almost ceased to be used and most of the charge chip manufacturers or completely stopped the release of chip for nickel batteries, or releases chips invariant to battery technology (so-called Multi-Chemistry IC). The Nomenclature of Stmicroelectronics is currently there are only microcircuits designed to work with lithium batteries.

Briefly remark the main features of lithium batteries.

Advantages:
. High specific electrical capacity. Typical values \u200b\u200bof 110 ... 160 W * Hour * kg, which is 1.5 ... 2.0 times higher than a similar parameter for nickel batteries. Accordingly, with equal dimensions of the lithium battery capacity above.
. Low self-discharge: approximately 10% per month. In nickel batteries, this parameter is 20 ... 30%.
. There is no "memory effect", due to which this battery is easy to maintain: there is no need to discharge the battery to a minimum before the next charging.

disadvantages Lithium batteries:
. The need for current protection and voltage. In particular, it is necessary to exclude the possibility of a short circuit of the battery conclusions, feeding the reverse polarity voltage, reloaded.
. The need to protect against overheating: the heating of the battery above a certain value negatively affects its capacity and service life.

There are two industrial production technologies for lithium batteries: lithium-ionic (Li-ion) and lithium polymer (Li-POL). However, since the charge algorithms of these batteries coincide, the charge chips do not share lithium-ion and lithium-polymer technologies. For this reason, the discussion of the advantages and disadvantages of Li-Ion and Li-Pol-batteries will miss, referring to the literature.

Consider the charge algorithm of lithium batteries represented on figure 1..

Fig. one

First phase, the so-called preliminary charge is used only in cases where the battery is highly discharged. If the battery voltage
below is 2.8 V, it cannot be immediately charged with the highest possible current: it will definitely affect the battery life. You must first "recharge" a small current battery for about 3.0 V, and only after that the charge will be allowed to be maximum.

Second phase: Charger as a DC source. At this stage, the maximum current flow through the battery is proceeded. At the same time, the battery voltage is gradually growing until it reaches the limit value of 4.2 V. Strictly speaking, at the end of the second stage, the charge can be terminated, but it should be borne in mind that the battery is currently charged about 70% of its container. Note that in many chargers, the maximum current is not applied immediately, and smoothly increases to a maximum for a few minutes - the smooth start mechanism is used (Soft Start).

If it is desirable to charge the battery to the values \u200b\u200bof the capacity close to 100%, then we turn to the third phase: the charger as a source of constant voltage. At this stage, a constant voltage of 4.2 V is applied to the battery, and the current flowing through the battery, during the charge decreases from the maximum to some predetermined minimum value. At the moment when the current value decreases to this limit, the battery charge is considered completed and the process is completed.

Recall that one of the key parameters of the battery is its container (unit unit - A * hour). Thus, the typical capacity of the lithium-ion battery of the AAA size is 750 ... 1300 mA * h. As a derivative of this parameter, the characteristic "Current 1C" is used, this is the value of the current numerically equal to the nominal capacity (in the example above - 750 ... 1300 mA). The value "Current 1C" makes sense only as the definition of the maximum current value when charging the battery and the current value at which the charge is considered complete. It is believed that the value of the maximum current should not exceed the value of 1 * 1C, and the battery charge can be considered complete with a decrease in current to a value of 0.05 ... 0.10 * 1c. But these are the parameters that can be considered optimal for a particular type of battery. In reality, the same charger can work with batteries of various manufacturers and different capacities, while the container of a particular battery remains unknown to the charger. Therefore, the battery charge of any capacity in the general case will not occur in the optimal for the battery mode, but in the mode pre-installed for the charger.

Let us turn to the consideration of the Stmicroelectronics charge chip lineup.

STBC08 and STC4054 chips
These chips are fairly simple products for lithium batteries. Microcircuits are made in miniature cases of type DFN6 and TSOT23-5L, respectively. This allows you to use these components in mobile devices with sufficiently stringent requirements for bulb characteristics (for example, cell phones, MP3 players). Inclusion schemes STBC08 and STC4054 are presented on figure 2..

Fig. 2.

Despite the limitations that impose the minimum number of external conclusions in the housings, chips have fairly wide functionality:
. There is no need to apply an external MOSFET transistor, a blocking diode and a current resistor. As follows figure 2.The outer strapping is limited by the filtering capacitor at the input, a programming resistor and two (for STC4054 - one) indicator LEDs.
. The maximum value of the charge current is programmed with a nominal external resistor and can reach 800 mA values. The end of the charge is determined at the moment when in constant voltage mode, the charging current value will decrease to 0.1 * i Bat, that is, is also given by the nominal value of the external resistor. The maximum charge current is determined from the ratio:
I Bat \u003d (V Prog / R Prog) * 1000;
where I BAT is a charge current in amperes, R Prog - resistance of the resistor in Omah, V Prog - voltage at the output P ROG, equal to 1.0 volt.
. In the mode of constant voltage at the outlet, a stable voltage is formed 4.2 V with accuracy not worse than 1%.
. The charge of highly discharged batteries is automatically starts from the pre-charging mode. As long as the voltage at the battery output does not reach the value of 2.9 V, the charge is carried out by a weak current of 0.1 * i Bat. A similar method, as already noted, prevents a very likely failure when trying to charge highly discharged batteries in the usual way. In addition, the value of the starting value of the charging current is forcibly limited, which also increases battery life.
. The automatic drip recharging mode is implemented - when the battery voltage is reduced to 4.05, the charge cycle will be restarted. This allows you to provide a permanent battery charge at a level not lower than 80% of its nominal container.
. Protection against overvoltage and overheating. If the input voltage value exceeds a certain limit (in particular, 7.2 V) or if the body temperature exceeds 120 ° C, the charger is turned off, protecting itself and battery. Of course, the defense against low input voltage is also implemented - if the input voltage dropped below a certain level (U VLO), the charger will also turn off.
. The ability to connect the LED indication allows the user to have an idea of \u200b\u200bthe current state of the battery charging process.

Battery Chickens L6924D and L6924U
Microcircuit data is devices with wider capabilities compared to STBC08 and STC4054. On the figure 3. Presented typical inclusion circuits L6924D and L6924U microcircuits.

Fig. 3.

Consider the functional features of the L6924 chip, which relate to the task of the battery charge parameters:
1. In both modifications, it is possible to set the maximum battery charge duration since the transition to the DC stabilization mode (the term "Quick Charging Mode" is also used - Fast Charge Phase). When you go to this mode, the watchdog timer is started, programmed to a certain duration T PRG the capacitor with the conclusion of the T PRG. If the battery charge is not terminated before the timer, the battery is not terminated (reducing the current flowing through the battery below i end), then after the timer is triggered, the charging will be interrupted. With the help of the same capacitor, the maximum pre-charging mode is set: it is 1/8 of the duration T PRG. Also, if during this time there was no transition to quick charging mode, the circuit shutdown.
2. Pre-charging mode. If for the STBC08 device, the current in this mode was set as a value of 10% of i Bat, and the switching voltage to the DC mode was fixed, then in the L6924U modification, this algorithm was preserved unchanged, but in the L6924D chip, both of these parameters are specified using external Resistors connected to inputs I Pre and V Pre.
3. Sign of charging completion in the third phase (constant voltage stabilization mode) in STBC08 and STC4054 devices as a value of 10% of I BAT. In chips L6924, this parameter is programmed by the nominal external resistor connected to the output I end. In addition, for the L6924D chip, it is possible to reduce the voltage value at the V OUT output from the generally accepted value of 4.2 V to a value of 4.1 V.
4. The value of the maximum charging current I PRG in these chips is set in a traditional way - by the nominal external resistor.
As we see, in simple "charging" STBC08 and STC4054, with the help of an external resistor, only one parameter is set - the charging current. All other parameters were either rigidly fixed, or were a function from I BAT. In chips L6924 there is the possibility of a fine adjustment of several more parameters and, in addition, "insurance" of the maximum duration of the battery charging process is carried out.

For both modifications, L6924 provides two modes of operation if the input voltage is formed by a network AC / DC adapter. The first is the standard mode of a linear lowering regulator of the output voltage. The second is the quasi-pulse regulator mode. In the first case, the current can be given a current, the value of which is slightly smaller than the magnitude of the input current taken from the adapter. In DC stabilization mode (second phase - Fast Charge Phase), the difference between the input voltage and the voltage on the "plus" batteries is dissipated as thermal energy, as a result of which the power dissipated on this charge phase is maximum. When operating in the mode of the pulse controller, the current can be given a current whose value is higher than the input current value. At the same time, "in heat" is significantly less energy. This, firstly, reduces the temperature inside the housing, and secondly - increases the efficiency of the device. But it should be borne in mind that the accuracy of current stabilization in linear mode is approximately 1%, and in a pulse - about 7%.

The operation of the L6924 chip in the linear and quasi-pulse modes is illustrated figure 4..

Fig. four

The L6924U microcircuit, in addition, can not work from the network adapter, but from the USB port. In this case, the L6924U microcircuit implements some technical solutions that allow you to further reduce the scattered power by increasing the cost of charging.

The L6924D and L6924U microcircuits have an additional input of forced charge interrupt (that is, shutdowns) SHDN.
In simple charge chips, the temperature protection consists in stopping the charge with an increase in the temperature inside the chip body up to 120 ° C. This, of course, is better than the complete absence of protection, but the value of 120 ° C on the housing with the temperature of the battery itself is more than conditionally connected. Products in products L6924 provides the ability to connect a thermistor directly related to the battery temperature (RT1 resistor in Figure 3). At the same time, it becomes possible to set the temperature range in which the battery charge will be possible. On the one hand, lithium batteries are not recommended to be charged at a minus temperature, and on the other, it is also extremely undesirable if the battery when charging heats up more than 50 ° C. The use of the thermistor makes it possible to charge the battery only under favorable temperature conditions.

Naturally, the additional functionality of the L6924D and L6924U microcircuits not only expands the possibilities of the designed device, but also leads to an increase in the area on the board, occupied by both the chip housing itself and the external elements of the strapping.

STBC21 Battery Charge Chokes and Stw4102
This is the further improvement of the L6924 chip. On the one hand, approximately the same functional package is implemented:
. Linear and quasi-pulse mode.
. The thermistor associated with the battery as a key element of temperature protection.
. The ability to set quantitative parameters for all three phases of the charging process.

Some additional features that were absent in L6924:
. Protection against incorrect polarity.
. Protection against short circuit.
. An essential difference from L6924 is the presence of digital interface I 2 C to specify the values \u200b\u200bof the parameters and other settings. As a result, more accurate charge settings are possible.

The recommended inclusion scheme STBC21 is shown on figure 5.. Obviously, in this case, the question of saving the area of \u200b\u200bthe board and the rigid mass-darling characteristics is not worth it. But it is also obvious that the use of this chip in small dictaphones, players and mobile phones of simple models is not expected. Rather, these are batteries for laptops and similar devices where the replacement of the battery is infrequent, but also notable.

Fig. five

The STBC21 and STW4102 chips do not belong to one family. Despite the fact that their basic functionality is similar, there are a significant amount of differences in small details. The STW4102 chip, for example, provides more opportunities in the "fine" settings of almost all possible parameters, moreover, additional battery monitoring functions are implemented, it is possible to use an external MOSFET transistor. However, the target area of \u200b\u200bapplication of both microcircuits is approximately the same.

Control / Indication Chips
The basis of the battery microcircuit line of any manufacturer is exactly the battery charge chip (Battery Chargers IC), which were considered above. But many manufacturers complement the nomenclature of "related" chips to which the battery status monitoring and battery level chips can be attributed to the Battery Gas Gauge (Battery Gas Gas Gauge) microcircuits. In the Stmicroelectronics nomenclature, both of these roles perform STC3100 and STC3105. The inclusion scheme STC3105 is presented on figure 6.. From a functional point of view, the microcircuit performs periodic measurements of the voltage values \u200b\u200bat the output of the chip and the current flowing through it. The obtained and processed data are transmitted to the microcontroller via channel I 2 C. These microcircuits, on the one hand, may be an effective addition for simple charge chips in applications where it makes no sense to complicate the charge procedure itself, but it may be useful to expand the process of control over the process. On the other hand, the interface I 2 C implies the presence of a microcontroller, which should receive data and, as a result, make some kind of solution based on them. But in this case, the decision to use the STBC21 and STW4102 intelligent chips, in which some monitoring functions are already implemented.

Fig. 6.

CC / CV controllers
In addition to the functionally completed battery charge chips, STMicroelectronics offers a CC / CV-controller chip family, in particular, the TSM101X series microcircuits. Microcircuit data includes a reference voltage source and two operating amplifiers, as a rule, with a combined output. On the figure 7. A fragment of a network charger circuit for a lithium battery using the TSM1012 controller is presented. On the first operating amplifier (CV - Constant Voltage), the contour of the stabilized constant voltage is implemented, on the second (CC - Constant Current) - the contour of the stabilized DC. The remaining components are a typical strapping of a pulse power supply and a set chain.

Fig. 7. ()

Recall that the lithium battery charge cycle consists of two phases in which the device acts as a DC source and one phase in which the device acts as a constant voltage source. Of course, the design of a charger based on universal "bricks" is a more troublesome and time consuming lesson, rather than the use of specialized schemes. However, in this case, it becomes possible to create devices in which some parameters turn out to be at a substantially different quality level. For example, a number of solutions are given in operation, allowing to significantly reduce the power consumption of the network charger in idle mode. Calculations are given according to which the typical solution provides the value of the total power consumed equal to 440 MW. Initial optimization of the scheme with the use of the TMS1011 controller gives a value of 140 MW, and further optimization of the circuit on the TMS1012 controller provides a further reduction in power up to 104 MW. Of course, in most cases you can do with typical solutions that are not recorded, but quite acceptable indicators. However, it is necessary to keep in mind that the fact that in the product line has components that allow, if necessary, develop a device with "elite" values \u200b\u200bof individual parameters.

DC / DC converters for solar panels
For most mobile devices with battery powered batteries, the charger is performed as an autonomous device for an AC household network. That is, in any case, an AC / DC transducer is required to form the input constant voltage for the battery chip. Stmicroelectronics offers a wide range of similar converters, as well as proven network adapter design technology. However, network chargers - although the most common, but not the only possible solution. As a source of energy, solar energy can be used, accumulated in solar panels. In the Nomenclature of Stmicroelectronics, there are DC / DC converter chips for solar panels using the MPPT algorithm (Maximum Power Point Tracking - tracking the maximum power point). Without going into specific details, we note that today MPPT technology is the most advanced and efficient technology for the solar battery charge controllers. Calculation of the maximum charge efficiency point from the solar module allows you to increase the efficiency of generating solar energy to 25 ... 30% compared with other types of controllers. At the moment, STMicroelectronics releases two chips - SPV1020 and SPV1040.

The first works with a chain of successively connected solar-voltage in the range of 6.5 ... 40 V. Second - as a rule, with one, battery voltage to 5.5 V. Stmicroelectronics also released the STEVAL-ISV012V1 demonstration board, which includes MPPT DC / DC transducer SPV1040 and L6924D charge chip.

Figure 8 shows a demo board.

The main problem when creating a portable device with an autonomous power source in the form of a battery is a charger, and more precisely, it is an element base that can be embedded in the device.
The main selection criteria are minimum body kit, 5V power, indication output, charge current within 500MA with the possibility of installation, low cost. It seems that the requirements are not so colossal, but each microcircuit has its own minuses that I will try to describe.

It all started with the BQ2057 microcircuit (PDF). I do not cite the connection scheme, because there is a datashet. First impressions - it works. The cost is not so high, but the presence of a large number of body parts (especially a current sensor) scares.

BQ2057.

Pros:
- The maximum charge current depends on the output transistor and shunt.
- There is a charge indication.

Minuses:
- Not very convenient for soldering housing TSSOP-8.
- Much body parts.

The verdict is ideal for external chargers, or devices with a large capacity of the battery for a large charge current.

The next microcham in this epopea was NCP1835 (PDF).
For some time, this chip was the perfect option for me. Not one design was collected with this microcircuit until they ended.
Characteristics and schema can be again viewed in the datashet.

NCP1835

Pros:
- The presence of charge indication.
- Charging timer with error indication.
- Minimum body parts.

Minuses:
- The housing is less than the previous one - DFN-10 (3x3mm).

The verdict is the perfect option for miniature devices, but complicates the manufacture of fees and installation, and the price is not the lowest, but quite acceptable.

After this microcircuit, I met Microchip - MCP73812 (PDF) products. An excellent is not an expensive microcircuit with a body kit in the form of a resistor, well, a spoon of tar is a lack of display, well, and as for me it is warm enough and I didn't really like it.

MCP73812.

Pros:
- Minimum body parts.
- Selecting current charge by an external resistor (not shunt).
- SOT23-5 case.

Minuses:
- No indication.
- Not very stable operation when cutting food.

The verdict is it, and is suitable for the simplest schemes where there is no need to indicate the charging process.

But now what my searches have shown about the reason for the reason for the satisfaction of all my requests (naturally in terms of the memory) - the IC chip, a cheaper option with the same functionality with LTC4054 - STC4054 (PDF).
With a price of 6 times from the original (up to $ 1), it meets all my requests, and is ideal for all designs.

STC4054.

LIR14500.

Pros:
- Minimum body parts.
- Selecting current charge by an external resistor (not shunt).
- SOT23-5 case.
- The presence of charge indication.
- Charge current up to 800mA.

Minuses:
- There are no understanding.

The verdict is the perfect price ratio, functional, size, simplicity of the scheme.

In this microcircuit, it was collected for LIR14500 for my

Battery is a common source of nutrition of various mobile devices, gadgets, robots ... Without it, the class of portable devices, probably, would not exist or would be not recognizable. One of the most modern types of batteries, lithium-ion and lithium polymer can be considered. But the device worked, the battery talked, now you need to use it the main difference from simple batteries - to charge.

The article will briefly describe two common chips (more precisely one common LTC4054 and its similar replacement of STC4054) charge of one bed Li-Ion batteries.

These chips are identical, the difference is only in the manufacturer and price. Another huge plus is a small amount of strapping - only 2 passive components: the input 1 μF capacitor and the current resistor. Optionally, you can add the LED - the indicator of the status of the charge process, burns - charging goes, went out - the charge is over. Supply voltage 4.25-6.5 V, i.e. Charging from the usual 5B, not a gift based on these chips, most of the simple charges of the USB are built. Charges up to 4.2V. Maximum current 800mA.

The basis of the LTC4054 or STC4054 charging circuit board. Input capacitor with a capacity of 1MKF size 0805. Clamping resistor 0805, resistance is calculated below. And LED 0604 or 0805 with a current-limiting size resistor 0805 at 680.

The resistor (or charge current) is calculated according to the following formulas:

Because Vprog \u003d ~ 1B, we obtain the following simplified formulas

Some examples of calculation:

I, Ma.	R, com
100	10
212	4,7
500	2
770	1,3

For the last pair of pictures of the version of the self-made USB charging for lithium polymer batteries of a small helicopter.

I liked small chips for simple charging devices. I bought them in our local offline store, but as they came out there ended, they were lucky for a long time. Looking at this situation, I decided to order them with a little wholesale, as the chips are quite good, and liked the work.
Description and comparison under the cut.

I did not in vain wrote in the title about the comparison, because during the way the dog could have grown up the microup appeared in the store, I bought a few pieces and decided to compare them.
The review will not have a lot of text, but quite a lot of photos.

But I will start as always with how it came to me.
It came complete with other different details, the Microuds themselves were packed in a bag with a latch and a sticker with the title.

This microcircuit is a chip of a charger for lithium batteries with a voltage of the charge 4.2 volt.
She knows how to charge batteries to 800mA.
The current value is set by the change in the nominal value of the external resistor.
It also maintains the function of charge with a small current if the battery is strongly discharged (the voltage is lower than 2.9 volts).
When charging up to voltage 4.2 volts and the drop in the charging current lower than 1/10 from the installed, the chip disables the charge. If the voltage falls to 4.05 volts, it will again go into charge mode.
There is also a way out for connecting the display LED.
More information can be found in, this chip there is much cheaper.
And he is cheaper with us, on the contrary, on the contrary.
Actually, for comparison, I bought analogue.

But what was my surprise when the LTC and STC chips were in appearance completely the same, both labeling - LTC4054.

Well, maybe even more interesting.
As everyone understands, the chip is so easy not to check, it is still necessary to the strapping from other radio components, preferably fee, etc.
And then, the comrade asked to fix (although in this context it is more red for) a charger for 18650 batteries.
Native burned down, and the charge current was small.

In general, for testing, you must first collect what we will test for.

I dwell on a datashet, even without a scheme, but I will give the scheme here for convenience.

Well, the actual printed fee. There are no VD1 and VD2 diodes on the board, they have been added after all.

All this was printed, transferred to the cutting of the textolite.
To save, I made another fee on trimming, a review with her participation will be later.

Well, in fact, the printed circuit board is made and the necessary parts are selected.

And I will remove such a charger, for sure it is very famous to readers.

Inside it is a very difficult scheme consisting of a connector, LED, a resistor and specially trained wires that allow you to align the charge on the batteries.
Just kidding, charger is in a block, included in the socket, and here simply 2 batteries connected in parallel and the LED constantly connected to the batteries.
To the native charger will return later.

Spread the scarf, said the native fee with the contacts, the contacts with the springs themselves dropped, they will still be useful.

He drilled a couple of new holes, on average there will be a LED displaying the inclusion of the device in the side - the charge process.

Puts a new board with springs, as well as LEDs.
LEDs are conveniently inserted into the fee, then carefully install the board to your native place, and only after that it will be sought, then they will stand smoothly and equally.

The board is installed in place, the power cable is soldered.
Actually, the printed fee was developed for three pickup options.
2 options with miniusb connector, but in the installation options from different sides of the board and under the cable.
In this case, I first did not know how the cable is needed, therefore weighed short.
Also soldered the wires that go to the plus contacts of batteries.
Now they go on separate wires, for each battery its own.

That's how it turned out on top.

Well, now let's go to testing

On the left on the board, I installed Ali Micrukhu bought on Ali, on the right purchased offline.
Accordingly, they will be mirrored on top.

First Micruma with Ali.
Charge current.

Now purchased offline.

Current KZ.
Similarly, first with Ali.

Now from offline.

There is a complete identity of the microcircuit, which is no means not to please :)

It was noted that at 4.8 volts of the charge current of 600mA, at 5 volts drops to 500, but it was checked after warming up, it may still work with overheating, I have not figured it out, but the chips behave approximately equally.

Well, now a little about the process of charging and refinement to rework (yes, even it happens).
From the very beginning, I thought to simply install the LED on the indication of the included state.
It seems everything is simple and obvious.
But as always, she wanted more.
I decided that it would be better if during the charge he would be repaid.
I added a pair of diodes (VD1 and VD2 in the diagram), but got a small bummer, the LED showing the charge mode shines and then when there is no battery.
Rather does not shine, but quickly flickers, added parallel to the terminals of the battery capacitor to the 47MCF, after that it began to flare up very shortly, almost imperceptibly.
This is exactly the hysteresis of switching on re-charging, if the voltage dropped below 4.05 volts.
In general, after this improved, everything was fine.
The battery charge, shines red, does not shine green and the LED shines where there is no battery.

The battery is fully charged.

In the off state of the microcircuit, does not pass the voltage to the power connector, and does not be afraid of the twist of this connector, respectively, does not discharge the battery to its LED.

Not without temperature measurement.
I got a little more than 62 degrees after 15 minutes of charge.

Well, here it looks like a fully finished device.
External changes are minimal, unlike internal. The power supply for 5 / volts 2 amps of the comrade was, and quite quite good.
The device provides a charge current of 600mA per channel, independent channels.

Well, so the native charger looked. Comrade wanted to ask me to raise the charging current in it. It also could not stand it, where else to lift, slag.

Summary.
In my opinion, for the chip for 7 cents is very good.
Microcircuits are fully functional and no different from purchased offline.
I am very pleased, now there is a stock of Microus and do not wait for them when they are in the store (recently disappeared from the sale).

Of the minuses, this is not a ready-made device, therefore it will have to run, soldering, etc., but there is a plus, you can make a fee for a specific application, and not to use what is.

Well, in Tog to get a work product made with your own hands, cheaper than finished fees, and even under your specific conditions.
Almost forgotten, datasheet, scheme and tracing -