BQ24745_14 Datasheet, PDF (28/39 Pages) Texas Instruments – SMBus-Controlled Multi-Chemistry Battery

bq24745
SLUS761D – DECEMBER 2007 – REVISED OCTOBER 2011
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REMOTE SENSE
The bq24745 has a dedicated remote sense pin, VFB, which allows the rejection of board resistance and
selector resistance. To use remote sensing fully, connect VFB directly to the battery interface through an
unshared battery-sense Kelvin trace, and place a 0.1-μF ceramic capacitor near the VFB pin to GND (see
Figure 1).
Remote Kelvin sensing provides higher regulation accuracy by eliminating parasitic voltage drops. Remote
sensing cancels the effect of impedance in series with the battery. This impedance normally causes the battery
charger to enter constant-voltage mode prematurely.
Component List for Typical System Circuit of Figure 2
Part Designator
Q1, Q2,
Q3, Q4
RAC, RSR
L1
D1
C1
C6
2xC13, C14, C15
C6, C16, C4, C8
C2, C3, C7, C9, C10, C17
C5
C23
C21
C22
R3, R4, R10, R11, R12
R1
R2
RC1
RC6
R19
R20
R21
R22
R7, R8
R18
Qty
Description
3 P-channel MOSFET, –30-V, –7.5-A, SO-8, Vishay-Siliconix, Si4435
2 N-channel MOSFET, 30-V, 12.5-A, SO-8, Fairchild, FDS6680A
2 Sense resistor, 10-mW, 2010, Vishay-Dale, WSL2010R0100F
1 Inductor, 5.6-uH, 7-A, 31-mΩ Vishay, IHLP2525CZ01-2R
1 Diode, dual Schottky, 30-V, 200-mA, SOT23, Fairchild, BAT54C
1 Capacitor, ceramic, 2.2-µF, 35-V, 10%, X7R
1 Capacitor, ceramic, 1-µF, 35-V, 10%, X7R
4 Capacitor, ceramic, 10-µF, 35-V, 20%, X5R, 1206, Panasonic, ECJ-3YB1E106M
4 Capacitor, ceramic, 1-µF, 25-V, 10%, X7R, 2012, TDK, C2012X7R1E105K
6 Capacitor, ceramic, 0.1-µF, 50-V, 10%, X7R, 0805, Kemet, C0805C104K5RACTU
1 Capacitor, ceramic, 100- pF, 25-V, 10%, X7R, 0805, Kemet
1 Capacitor, ceramic, 51-pF, 25-V, 10%, X7R, 0805, Kemet
1 Capacitor, ceramic, 2000-pF, 25-V, 10%, X7R, 0805, Kemet
1 Capacitor, ceramic, 130-pF, 25-V, 10%, X7R, 0805, Kemet
5 Resistor, chip, 10-kΩ, 1/16-W, 5%, 0402
1 Resistor, chip, 309-kΩ, 1/16-W, 1%, 0402
1 Resistor, chip, 49.9-kΩ, 1/16-W, 1%, 0402
1 Resistor, thick film chip paralleling, 2× 3.9-Ω, 25-V, 1210
1 Resistor, thick film chip , 10-Ω, 1206
1 Resistor, chip, 7.5-kΩ, 1/16-W, 5%, 0402
1 Resistor, chip, 20-kΩ, 1/16-W, 1%, 0402
1 Resistor, chip, 200-kΩ, 1/16-W, 5%, 0402
1 Resistor, chip, 100-Ω, 1/16-W, 1%, 0402
2 Resistor, chip, 200-kΩ, 1/16-W, 1%, 0402
1 Resistor, chip, 1.4-MΩ, 1/16-W, 1%, 0402
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