Datasheet

 
 
SLUS025F − MAY 2001 − REVISED JULY 2002
11
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APPLICATION INFORMATION
Figure 5. High-Side Current Sensing Figure 6. Low-Side Current Sensing
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
R
SNS
BAT+
BAT−
SNS
BAT
VCC
TS
COMP
CC
VSS
STAT
bq2057
DC+
DC−
R
SNS
BAT+
BAT−
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:
R
B1
R
B2
+
ǒ
N
V
(CELL)
V
O(REG)
Ǔ
–1
Where:
N = Number of cells in series
V
(CELL)
= Desired regulation voltage per cell
(2)