Datasheet

bq24725A
SLUSAL0 –SEPTEMBER 2011 www.ti.com
Pin Functions – 20-Pin QFN (continued)
PIN
DESCRIPTION
NO. NAME
12 SRN Charge current sense resistor negative input. SRN pin is for battery voltage sensing as well. Connect SRN pin to a 7.5
Ω resistor first then from resistor another terminal connect a 0.1µF ceramic capacitor to GND for common-mode filtering
and connect to current sensing resistor. Connect a 0.1µF ceramic capacitor between current sensing resistor to provide
differential mode filtering. See application information about negative output voltage protection for hard shorts on battery
to ground or battery reverse connection by adding small resistor.
13 SRP Charge current sense resistor positive input. Connect SRP pin to a 10 Ω resistor first then from resistor another terminal
connect to current sensing resistor. Connect a 0.1µF ceramic capacitor between current sensing resistor to provide
differential mode filtering. See application information about negative output voltage protection for hard shorts on battery
to ground or battery reverse connection by adding small resistor.
14 GND IC ground. On PCB layout, connect to analog ground plane, and only connect to power ground plane through the power
pad underneath IC.
15 LODRV Low side power MOSFET driver output. Connect to low side n-channel MOSFET gate.
16 REGN Linear regulator output. REGN is the output of the 6V linear regulator supplied from VCC. The LDO is active when
voltage on ACDET pin is above 0.6V and voltage on VCC is above UVLO. Connect a 1µF ceramic capacitor from
REGN to GND.
17 BTST High side power MOSFET driver power supply. Connect a 0.047µF capacitor from BTST to PHASE, and a bootstrap
Schottky diode from REGN to BTST.
18 HIDRV High side power MOSFET driver output. Connect to the high side n-channel MOSFET gate.
19 PHASE High side power MOSFET driver source. Connect to the source of the high side n-channel MOSFET.
20 VCC Input supply, diode OR from adapter or battery voltage. Use 10Ω resistor and 1µF capacitor to ground as low pass filter
to limit inrush current.
PowerPAD Exposed pad beneath the IC. Analog ground and power ground star-connected only at the PowerPad plane. Always
solder PowerPad to the board, and have vias on the PowerPad plane connecting to analog ground and power ground
planes. It also serves as a thermal pad to dissipate the heat.
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