Features

* It is suitable for single batteries (4.1V or 4.2V) and dual batteries (8.2V or 8.4V) lithium ions or lithium polarized battery packs

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[ 123] * You need a small amount of external components

* 0.3V voltage drop, maximize heat dissipation

* in the place At the preset voltage, the voltage adjustment accuracy is better than ± 1%

* AutoCom's internal impedance of the battery pack to shorten the charging time

*[123 ] Optional battery temperature monitoring before and during charging

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Integrated voltage and current regulation with a programmable charging current and high or low -side currents ]* Integrated cell regulation used for recovery

-Early discharge battery and minimized heat

-The dissipation of the initial stage of charge

*[ 123] Single or dual LED or host processor interface charging status output

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Automatic battery charging function

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minimum current termination charging [ 123] *

The automatic low -power sleep mode when removing VCC

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EVMS can be used for fast assessment

*

Packaging: 8-pin SOIC, 8-needle TSSOP, 8-needle MSOP

Instructions

benchmark

BQ2057 series of advanced lithium ions (Li-agit) and lithium aggregation Linelian charge management integrated circuits are designed for cost-sensitive and compact portable electronic products. They integrated high -precision current and voltage adjustment, battery adjustment, temperature monitoring, charging termination, charging state indication, and automatic adjustment charging rate compensation in a 8 -stitched circuit. MSOP, TSSOP and SOIC packaging options are suitable for extensive terminal applications.

BQ2057 continuously measures the battery temperature with external thermistor. For safety reasons, BQ2057 is banned from charging until the battery temperature is within the threshold defined by the user. BQ2057 then charged the battery three -phase: adjustment, constant current and constant voltage. If the battery voltage is lower than the low voltage threshold V (min), the BQ2057 will use a low current to pre -charged the battery. The adjustment of the charging ratio is about 10%of the adjustment current. In the initial stage of the charging, the adjustment current will also minimize the heat dissipation of external power components. After the adjustment, the BQ2057 applied a constant current on the battery. External sensing resistorSet current. The sensor can be located at the high or low side of the battery without any additional components. The constant stream continues to the battery to reach the charging regulating voltage.

Then, BQ2057 began the constant pressure stage. In the working temperature and power supply voltage range, the voltage adjustment accuracy is better than ± 1%. For single batteries and dual batteries, there are four fixed voltage versions of BQ2057: 4.1V, 4.2V, 8.2V, and 8.4V. When the current is gradually reduced to the charging termination threshold I (terminal), the charging stops. If the battery voltage is lower than the V (RCH threshold), the BQ2057 will automatically start charging. )

The designer can also use the AutoCOMP function to reduce the charging time. This patent technology allows safety and dynamic compensation to the internal impedance charging of the battery pack.

Figure Figure

Terminal function

Details Explanation

current detection input

The battery current is performed by the voltage generated by the external sensing resistor on the pin. The external resistor can be placed on the high or low side of the battery. (See the schematic diagram for details)

Battery voltage input

The voltage sensor input directly connected to the positive electrode of the battery.

Temperature sensing input

Input of the temperature monitoring circuit of external battery. Connecting this input to VCC/2 will disable this function.

Charging status output

Three -state instructions for charging, completion of charging, temperature failure, or sleep mode.

The charge control output

The source of the source follower output, driving the external interior through the transistor (PNP or P channel MOSFET), the current and voltage are adjusted.

Treat compensation input

Setting rate compensation level. The voltage adjustment output is programmable to change the charging current transported to the battery.

Power supply voltage input

Power input and current reference of high -voltage side sensing configuration.

Application information

Function description

BQ2057 is an advanced linear charge controller for single battery or dual battery Lithium ions or lithium polarization applications. Figure 1 shows the schematic diagram of the charger using the PNP transistor. Figure 2 is the operating status diagram, Figure 3 is a typical charge distribution diagram. Figure 4 shows the schematic diagram of the charger using the P field MOSFET.

Qualification and pre -charging

When the battery is powerThe existence or battery has been inserted, and the BQ2057 starts charging cycle. Charging confirmation is based on battery temperature and voltage. If the battery temperature exceeds the range of V (TS), the BQ2057 will be suspended until the battery temperature is within the allowable range. BQ2057 also checked the battery voltage. If the battery voltage is lower than the pre -charging threshold V (minimum value), the BQ2057 uses a pre -charged to adjust the battery. Adjusting the charging ratio I (Prechg is set to about 10%of the regulating current. In the early stage of charging, adjusting the current will also minimize the heat dissipation of external channel components. Typical charge distribution is shown in Figure 3.

The current adjustment phase BQ2057 adjusts the current when the battery pack voltage is lower than the regulating voltage V. BQ2057 monitors the SNS input point through the voltage of the sensor R in series with the battery pack. The charging current. In the high -voltage side current influenza (Figure 5), R is between the VCC and SNS pin, in the low -voltage side current (Figure 6), R is located in VSS (battery negative pole) and SNS (charger grounded ground ground ground ) Between pins. The charging current feedback applied by the pin SNS, keep the V (SNS) voltage on the current detection resistor.

Among them, IO (REG) is the required charging current.

Voltage adjustment phase

Voltage adjustment feedback through the BAT pin. This input is directly input The positive electrode connected to the battery pack. BQ2057 monitor the voltage between the battery pack between the battery and the VSS pin. The BQ2057 has four fixed voltage versions: 4.1V, 4.2V, 8.2V, and 8.4V.

Other adjustments The voltage can be achieved by adding a divisioner between the positive electrode and the negative pole terminal of the battery pack and using the BQ2057T or BQ2057W. The resistance values of the device Rb1 and RB2 are calculated through the following formulas:

In the formula: n the number of units in series; V (battery) the adjustment voltage required by each battery.

Charging termination and charging

BQ2057 monitors the charging current during the voltage adjustment stage. BQ2057 declares a complete condition and gradually decreases to the charging termination threshold at the current current. I (TERM) terminate the charging. When a new battery voltage is lower than the V (RCH) threshold, the charging cycle begins.

Battery temperature monitoring The voltage between the between it is continuously monitored. Negative or positive temperature coefficient thermistor (NTC, PTC) and external compressors generate this voltage. (SeeFigure 9) BQ2057 compares the voltage with its internal V (TS1) and V (TS2) threshold to determine whether it is allowed to charge. (See Figure 10.) Temperature sensing circuit is not affected by any fluctuations in VCC, because the external pressure and internal threshold (V (TS1) and V (TS2)) are referred to the VCC.

The resistance values of R (T1) and R (T2) are calculated by the following procedures:

It is used for NTC thermistor

Battery temperature monitoring

used in PTC thermistor

in type, R (TC) is the cold resistance of thermistor resistance, R (Th) is the Thermal resistance of thermistor, such as thermal resistance manufacturers.

If you only need a temperature (heat or cold) settings, you can omit RT1 or RT2. The voltage between the V (TS1) and V (TS2) thresholds is applied to the pins TS to disable the temperature sensing function.

The charge inhibitory function

TS pin can be used as charge input input. Users can suppress charging by connecting TS PIN to VCC or VSS (or V (TS1) to any level outside the V (TS2) threshold). The voltage between V (TS1) and V (TS2) threshold is applied to the tube foot TS to restore the charger to normal work.

Charging status indicator

BQ2057 reports the status of the charger on the 3 state statistical tube. The following table summarizes the operation of STAT PIN.

The STAT pin can be used to drive a single LED (Figure 1), dual chip LED (Figure 4) or host or system processor interface (Figure 11). When the BQ2057 is connected to the processor, the user can use the output port (as shown in Figure 11) to identify the High-Z state of STAT PIN. In this configuration, users need to read the input pipe foot, switch output port, and read the STAT tube foot again. Under high Z conditions, the input port always matches the signal level on the output port.

Low -power sleep mode

If the VCC is lower than the voltage of the BAT input terminal, the BQ2057 enters the sleep mode. This function can prevent battery packs without VCC.

Selection of external transistor

BQ2057 Design for PNP transistor and P -channel MOSFET. In the case of a given circuit parameter, PCB layout, and radiator configuration, you should choose the device that can handle the required power consumption.

The following example illustrates the design process of any device:

PNPCrystal tube:

The choice of PNP bipolar crystal tube: for example: V i 4.5V, i (reg) 1A, 4.2V single battery lithium ion (BQ2057C). VI is the input voltage of the charger, and i (REG) is the required charging current (see Figure 1).

1. Determine the maximum power consumption PD in the transistor.

In the worst case, the power consumption occurs at the lowest time when the battery voltage V (BAT) is the lowest (usually the beginning of the 3V current regulation phase) and VI at the maximum value.

Among them, VCS is a voltage drop on the current detection resistor.

2. Determine the required packaging size in order to keep the connection temperature below the manufacturer's recommendation value T (J) MAX. Calculate the total θ and θ (℃/w).

Select a device package with at least 10%below this value to explain other θ except the device. For example, SOT223 package is usually 60 ° C/W.

3. Select a set of electrode-transmitting pole voltage, V (CE), the rated value is greater than the maximum input voltage. In this example, 15 volt devices are enough.

4. Select the device with the amount of the drain current IC at least 50%higher than the required charging current I (REG).

5. Use the following formulas, calculate the minimum (β or HFE) required for calculation:

where IMAX (c) is the largest collector current current (The same as I (REG) in this example), IB is the base current (selected as 35mA in this example).

Note: The BETA of the transistor decreases 3 times compared with the temperature and decreases as the load increases.

Therefore, when selecting the device, please pay attention to the β and minimum environmental temperature of the device under i (REG). This test version should be greater than the minimum test version required.

Select a PNP transistor now, its rated voltage is V (CE) ≥15V, θjc ≤ 78 ° C/W, IC≥1.5A, βmin ≥28, and is a SOT223 packaging.

P -channel MOSFET:

The selection steps of P -channel MOSFET: for example: V i 5.5V, I (reg) 500mA, 4.2V single battery lithium ion (BQ2057C). VI is the input voltage of the charger, and i (REG) is the required charging current. (See Figure 4.)

1. Determine that the transistor is at the lowest value (usually at the beginning of the current adjustment stage at the beginning of the current regulation) and VI is at the maximum value, and the worst case will occur. Power consumption.

Among themThe forward voltage drop of) VCS is the voltage drop of the current detection resistor.

2. Determine the required packaging size so that the joint temperature can be kept below the manufacturer's recommendation value TJMAX. Calculate the total θ and θ (℃/w).

Select a device package with at least 10%below this value to illustrate other reasons except the device. For example, the θ of the TSSOP-8 package is usually 70 ° C/W.

3. Select the missing source voltage V (DS), and the rated value is greater than the maximum input voltage. In this example, the 12 V device is enough.

4. Select the device with a rated value of the drain current (ID) at least 50%higher than the required charging current I (REG).

5. Confirm that the available driver can be large enough to provide the required charging current.

Among them, V (GS) is a gate to source voltage, VD is the positive voltage of the reverse blocking diode (if used), VCS is the current detection resistor For voltage drop, VOL (CC) is the output low voltage specification of the CC pin BQ2057.

Select the grid threshold voltage V (GSTH), and the rated value is less than the MOSFET with the calculation value V (GS).

Now select a P-channel MOSFET transistor, its rated voltage is VDS ≤ 15V, θjc ≤110 ° C/W, ID≥1A, V (GSTH) ≥ -3.5V, and in tssop packaging Essence

Select the input capacitor

In most applications, only a high -frequency decoupling capacitor is required. 0.1 μF ceramic placed near VCC and VSS pins work well. BQ2057 is suitable for regulating and non -regulating external DC power supply. If the non -regulating power supply is selected, the power unit should have sufficient capacitors to keep the power supply voltage at the required minimum input voltage under the maximum load. Otherwise, more capacitors must be added to the input end of the charger.

Select the output capacitor

BQ2057 does not require any output capacitors to ensure the stability of the ring. When the battery does not exist, the user can add an output capacitor to control the output voltage. The charger quickly charged the output capacitor to the adjustment voltage, but due to the low leakage current on the battery pins, the output voltage attenuation was slow to the charging threshold. For example, adding 0.1 μF ceramic capacitors can produce 100 MV (PP) pattern waveforms with a frequency of about 25Hz. If you need a lower frequency, you can use higher capacitance.

Automatic rate compensation

In order to reduce charging time, BQ2057 adopted a proper automatic compensation technology to safely compensate the internal impedance of the battery pack. By configured in high -voltage side current configurationConnect the Comp Pin to the VCC and connect the COP PIN to VSS in the low -voltage side current configuration. The compression machine cannot be sold.

FIG. 12 outlines the main components of the single battery lithium -ion battery pack. The lithium -ion battery pack is composed of batteries, protection circuits, fuses, connectors, current response resistors and some wiring. Each of these components contain some resistance. The total impedance of the battery pack is the sum of the minimum resistance of all battery components. Using the minimum resistance value can reduce the possibility of excessive compensation. Excessive compensation may activate the safety circuit of the battery pack.

Compensation is implemented by input pin COMP (Figure 13). Through part of the current response voltage displayed by this pin, press the factor of G (com about) to be zoomed in, and adds to the adjustment threshold VO (reg). This process will increase the output voltage to compensate for the internal impedance of the battery pack and the non -expected voltage drop in the circuit.

Compensation of automatic rates

AutoComp installation program requires the following information:

-Cathemons total impedance (Z (PACK))

-D maximum charging current (I (reg))

The following formula calculations can be used through the voltage drop of the internal impedance of the battery pack:

and then use the following formula calculation Required compensation:

Among them, V (COMP) is the voltage on the COMP pin. This voltage refers to the VCC in the high -voltage side current configuration, and refer to the VSS in the low -voltage sensor configuration. V (PACK) is the voltage on the battery pack.

The values of R (COMP1) and R (COMP2) can be calculated using the following formulas:

The following examples illustrate these calculations:

] Suppose Z (PACK) 100 MΩ, i (reg) 500 mAh, high -voltage -side electric fluch BQ2057C

The closest standard value of RCOMP1 (36.0 kΩ (36.0 kΩ To.

Mechanical data

Note:

1. Control size: millimeter. The inch is for reference only.

2. D " and "E " do not include mold flying or protruding objects. Each side of the mold may not exceed 0.15 mm

3. The center line of each wire shall be within the ± 0.10 mm range of its accurate position.

4. The lead should be in the coexistence of the seat surface 0.08 mm.123]

5. The size "B " does not include protruding rods.Dam bars should not cause the width of the wires to exceed the maximum value of "B " by more than 0.08 mm.

6. The size is suitable for the flat cross section between 0.10 mm and 0.25 mm from the tip of the lead.

7. "A1 " refers to the distance from the plane plane to the packaging body (base surface).

Tape and curl information

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