BQ24735_17 Datasheet, PDF (3/46 Pages) Texas Instruments – 1- to 4-Cell Li+ Battery SMBus Charge Controller for Supporting Turbo Boost Mode With N-Channel Power MOSFET Selector

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bq24735
SLUSAK9B – SEPTEMBER 2011 – REVISED APRIL 2015
5 Description (continued)
The bq24735 device uses an internal input current register or an external ILIM pin to throttle down PWM
modulation to reduce the charge current. The bq24735 device charges 1-, 2-, 3-, or 4-series Li+ cells.
6 Pin Configuration and Functions
RGR Package
20-Pin VQFN
Top View
20 19 18 17 16
ACN 1
ACP 2
CMSRC 3
ACDRV 4
ACOK 5
bq24735
15 LODRV
14 GND
13 SRP
12 SRN
11 BATDRV
6 7 8 9 10
PIN
NAME
ACDET
ACDRV
ACOK
ACN
ACP
BATDRV
BTST
CMSRC
GND
HIDRV
Pin Functions
DESCRIPTION
NO.
Adapter detection input. Program adapter valid input threshold by connecting a resistor divider from adapter input to
6 ACDET pin to GND pin. When ACDET pin is above 0.6 V and VCC is above UVLO, REGN LDO is present, ACOK
comparator and IOUT are both active.
Charge pump output to drive both adapter input N-channel MOSFET (ACFET) and reverse blocking N-channel
MOSFET (RBFET). ACDRV voltage is 6 V above CMSRC when voltage on ACDET pin is between 2.4 V and 3.15 V,
4 voltage on VCC pin is above UVLO and voltage on VCC pin is
275 mV above voltage on SRN pin so that ACFET and RBFET can be turned on to power the system by AC adapter.
Place a 4-kΩ resistor from ACDRV to the gate of ACFET and RBFET limits the inrush current on ACDRV pin.
AC adapter detection open-drain output. It is pulled HIGH to external pullup supply rail by external pullup resistor
when voltage on ACDET pin is between 2.4 V and 3.15 V, and voltage on VCC is above UVLO and voltage on VCC
5 pin is 275 mV above voltage on SRN pin, indicating a valid adapter is present to start charge. If any one of the above
conditions cannot be met, it is pulled LOW to GND by internal MOSFET. Connect a 10-kΩ pullup resistor from ACOK
to the pullup supply rail.
1
Input current-sense resistor negative input. Place an optional 0.1-µF ceramic capacitor from ACN to GND for
common-mode filtering. Place a 0.1-µF ceramic capacitor from ACN to ACP to provide differential-mode filtering.
2
Input current-sense resistor positive input. Place a 0.1-µF ceramic capacitor from ACP to GND for common-mode
filtering. Place a 0.1-µF ceramic capacitor from ACN to ACP to provide differential-mode filtering.
Charge pump output to drive battery-to-system N-channel MOSFET (BATFET). BATDRV voltage is 6 V above SRN
11
to turn on BATFET to power the system from battery. BATDRV voltage is SRN voltage to turn off BATFET to power
system from AC adapter. Place a 4-kΩ resistor from BATDRV to the gate of BATFET limits the inrush current on
BATDRV pin.
17
High-side power MOSFET driver power supply. Connect a 0.047-µF capacitor from BTST to PHASE, and a bootstrap
Schottky diode from REGN to BTST.
3
ACDRV charge pump source input. Place a 4-kΩ resistor from CMSRC to the common source of ACFET (Q1) and
RBFET (Q2) limits the inrush current on CMSRC pin.
14
IC ground. On PCB layout, connect to analog ground plane, and only connect to power ground plane through the
power pad underneath IC.
18 High-side power MOSFET driver output. Connect to the high-side N-channel MOSFET gate.
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