BQ24725A_17 Datasheet, PDF (4/47 Pages) Texas Instruments – 1-4 Cell Li+ Battery SMBus Charge Controller with N-Channel Power MOSFET Selector and Advanced Circuit Protection

bq24725A
SLUSAL0A – SEPTEMBER 2011 – REVISED AUGUST 2014
www.ti.com
PIN
NO. NAME
12 SRN
13 SRP
14 GND
15 LODRV
16 REGN
17 BTST
18 HIDRV
19 PHASE
20 VCC
PowerPAD™
Pin Functions (continued)
DESCRIPTION
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.
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.
IC ground. On PCB layout, connect to analog ground plane, and only connect to power ground plane through the power
pad underneath IC.
Low side power MOSFET driver output. Connect to low side n-channel MOSFET gate.
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.
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.
High side power MOSFET driver output. Connect to the high side n-channel MOSFET gate.
High side power MOSFET driver source. Connect to the source of the high side n-channel MOSFET.
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.
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.
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)^{(1) (2)}
VALUE
UNIT
MIN
MAX
SRN, SRP, ACN, ACP, CMSRC, VCC
–0.3
30
PHASE
–2
30
ACDET, SDA, SCL, LODRV, REGN, IOUT, ILIM, ACOK
–0.3
7
Voltage range
BTST, HIDRV, ACDRV, BATDRV
LODRV (2% duty cycle)
–0.3
36
–4
7
V
HIDVR (2% duty cycle)
–4
36
PHASE (2% duty cycle)
–4
30
Maximum difference SRP–SRN, ACP–ACN
voltage
–0.5
0.5
Junction temperature range, T_J
–40
155
°C
(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) All voltages are with respect to GND if not specified. Currents are positive into, negative out of the specified terminal. Consult Packaging
Section of the data book for thermal limitations and considerations of packages.
4
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