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DV2057/C/T/W
Advanced Li-Ion Charger Development System Control of On-Board Linear Regulator
Features
bq2057 charge-control evaluation and development system for single- and dual-cell Li-Ion packs with coke or graphite anodes Optional temperature monitoring before and during charge Proprietary AutoComp charge-rate compensation Integrated trickle-charge for conditioning deeply discharged batteries Regulated charge current and voltage Charge status output for LED or host-processor interface to indicate charge-in-progress, full-capacity, and fault conditions Automatic battery-re-charge feature Charge termination by minimum current Direct battery connection 500mA charge rate High-side current sensing approximately 10% of the regulation current. The conditioning current also minimizes heat dissipation in the external pass element during the initial stage of charge. Once the battery voltage reaches the internal threshold, VMIN, full charge begins. The DV2057/C/T/W complete the charge cycle in two phases. While the pack is below the regulation voltage, a constant-current phase replenishes approximately 70% of battery capacity. An accurate voltage-regulation phase completes the charge. The DV2057/C/T/W terminate charge when the current tapers off to the VTERM threshold. These boards feature the proprietary AutoComp technique to compensate safely for the internal impedance of the battery. The AutoComp resistors, R COMP1 , and RCOMP2, must be set according to the characteristics of the battery. Before using these development boards, please review the bq2057 data sheet.

General Description
The DV2057/C/T/W are complete development and evaluation environments for bq2057 series advanced Li-Ion linear charge management ICs. The DV2057 family supports both single- and dual-cell Li-Ion packs with coke or graphite anodes: Part Number DV2057 DV2057C DV2057T DV2057W Regulation Voltage 4.1V 4.2V 8.2V 8.4V
Connection Descriptions
J1 DC+ DCJ2 BAT+ BATJ3 TEM+ INH Thermistor connection Charge inhibit input Positive battery terminal Negative battery terminal Charger supply positive Charger supply ground
Full charge is preceded by charge qualification based on battery temperature and voltage. The DV2057/C/T/W suspend charge if the battery temperature is outside the VTS1 to VTS2 thresholds and wait until the battery temp e r a t u r e i s w i t h i n t h e a l l o w e d r a n g e. T h e DV2057/C/T/W also check the battery voltage. If the battery voltage is below the low-voltage threshold, VMIN, the DV2057/C/T/W use trickle charge to condition the battery. The conditioning charge rate, I COND, is set at
SLUU056 - FEBRUARY 2000
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DV2057/C/T/W Configuration
These boards have the following characteristics: As configured, charge can be inhibited by connecting the INH input to DC+ or DC-. The value of R2 at shipment is 0.2. This resistor can be changed to suit the application. However, the maximum power dissipation in Q1 should not exceed the PD rating. (See recommended DC Operating Conditions.)
DV2057/C/T/W Regulation Voltages
Part Number DV2057 DV2057C DV2057T DV2057W Regulation Voltage 4.1V 4.2V 8.2V 8.4V
Setup Procedure
1. 2. Connect the battery pack to J1. Connect the charging supply to J2.
See the bq2057 data sheet for information on configuring the temperature sensing circuit and the AutoComp feature. As shipped the DV2057/C/T/W uses a bipolar transistor (Q1). Optionally, the user may replace Q1 with a P-channel MOSFET. Please refer to the schematic for details.
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Supply connector J1 accepts a maximum of 16VDC (See the limitation on power dissipation below.) Charge begins after application of both of the following: - - the battery supply voltage
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I I
Temperature sensing: disabled AutoComp: disabled
The on-board regulator supplies a charging current of 500mA. This current is controlled by the value of the sense-resistor, R2 in the following equation: ICHG = 0.100 R2
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DV2057/C/T/W DV2057/C/T/W Schematic
J1
1 2
DC+ DC-
D1 ZHCS1000
R2 0.2
Q1 FZT788B
J2 C2 1F 3 R4 R1 1.0k RCOMP2 1 RCOMP1
BAT+ BAT1 2
2
U1A
1 2 3 4
R3 2K
D2 LED
8 COMP SNS 7 CC BAT 6 VCC 5 VSS STAT TS
RT1 1.5M
TEMP+ INH
J3
1 2
bq2057 SOIC C1 0.1 RT2 1.5M U1B
8 COMP SNS 7 CC BAT 6 VCC VSS 5 STAT TS 1 2 3 4
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Notes: 1 As shipped: RCOMP1 = open circuit RCOMP2 = 0 Development Board DV2057 DV2057C DV2057T DV2057W Part Number bq2057SN or bq2057TS bq2057CSN or bq2057CTS bq2057TSN or bq2057TTS bq2057WSN or bq2057WTS
bq2057 TSSOP
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For use with a bipolar transistor: (Q1 is FZT788B) R1 = 1.0k R4 = open circuit For use with a MOSFET: (Q1 is BSP171P (Infineon)) R1 = 100 R4 = 1.0k ZHCS1000 and FZT788B are made by Zetex, Inc.
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DV2057/C/T/W Recommended DC Operating Conditions
Symbol VDC ICHG VTHERM VINH VBAT PD Description Input DC voltage Battery charge current Therm input voltage Inhibit input voltage BAT input voltage Power dissipation Minimum VBAT +0.5 0 0 0 Typical See Regulation Voltages Table. Maximum 15 500 VDC VDC VDC 1.75 Unit V mA V V V W At 40C ambient temperature Notes See Note. See Note.
Note: Power dissipation must not exceed the maximum PD rating. PD = ICHG (VDC - VBAT)
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Copyright (c) 2000, Texas Instruments Incorporated
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