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| BQ2057CTSTRG4 Datasheet, PDF (11/30 Pages) Texas Instruments – ADVANCED LINEAR CHARGE MANAGEMENT IC FOR SINGLE-AND TWO-CELL LITHIUM-ION AND LITHIUM-POLYMER | |||
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DC+
RSNS
DCâ
bq2057
SNS
COMP
BAT
CC
VCC
VSS
TS
STAT
APPLICATION INFORMATION
DC+
BAT+
BATâ
DCâ
bq2057, bq2057C
bq2057T, bq2057W
SLUS025F â MAY 2001 â REVISED JULY 2002
bq2057
SNS
COMP
BAT
VCC
CC
VSS
TS
STAT
RSNS
BAT+
BATâ
Figure 5. High-Side Current Sensing
Figure 6. Low-Side Current Sensing
voltage regulation phase
The voltage regulation feedback is through the BAT pin. This input is tied directly to the positive side of the
battery pack. The bq2057 monitors the battery-pack voltage between the BAT and VSS pins. The bq2057 is
offered in four fixed-voltage versions: 4.1 V, 4.2 V, 8.2 V and 8.4 V.
Other regulation voltages can be achieved by adding a voltage divider between the positive and negative
terminals of the battery pack and using bq2057T or bq2057W. The voltage divider presents scaled battery-pack
voltage to BAT input. (See Figure 7 and Figure 8.) The resistor values RB1 and RB2 for the voltage divider are
calculated by the following equation:
Ç Ç RB1
RB2
+
N
V(CELL)
VO(REG)
â1
(2)
Where:
N = Number of cells in series
V(CELL) = Desired regulation voltage per cell
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