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

bq24735
SLUSAK9B – SEPTEMBER 2011 – REVISED APRIL 2015
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Pin Functions (continued)
PIN
NAME
ILIM
IOUT
LODRV
PHASE
PowerPAD™
REGN
SCL
SDA
SRN
SRP
VCC
DESCRIPTION
NO.
Charge current limit input. Program ILIM voltage by connecting a resistor divider from system reference 3.3-V rail to
10
ILIM pin to GND pin. The lower of ILIM voltage or DAC limit voltage sets charge current regulation limit. To disable
the control on ILIM, set ILIM above 1.6 V. Once voltage on ILIM pin falls below 75 mV, charge (buck mode) or
discharge (boost mode) is disabled. Charge and discharge is enabled when ILIM pin rises above 105 mV.
Buffered adapter or charge current output, selectable with SMBus command ChargeOption(). IOUT voltage is 20
7 times the differential voltage across sense resistor. Place a 100-pF or less ceramic decoupling capacitor from IOUT
pin to GND.
15 Low-side power MOSFET driver output. Connect to low-side N-channel MOSFET gate.
19 High-side power MOSFET driver source. Connect to the source of the high-side N-channel MOSFET.
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.
Linear regulator output. REGN is the output of the 6-V linear regulator supplied from VCC. The LDO is active when
16 voltage on ACDET pin is above 0.6 V and voltage on VCC is above UVLO. Connect a 1-µF ceramic capacitor from
REGN to GND.
9
SMBus open-drain clock input. Connect to SMBus clock line from the host controller or smart battery. Connect a 10-
kΩ pullup resistor according to SMBus specifications.
8
SMBus open-drain data I/O. Connect to SMBus data line from the host controller or smart battery. Connect a 10-kΩ
pullup resistor according to SMBus specifications.
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 another resistor terminal, connect a 0.1-µF ceramic capacitor to GND for common-
12 mode filtering, and connect to current-sensing resistor. Connect a 0.1-µF ceramic capacitor between current-sensing
resistor to provide differential-mode filtering. See Application and Implementation 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 another resistor
13
terminal, connect to current-sensing resistor. Connect a 0.1-µF ceramic capacitor between current-sensing resistor to
provide differential-mode filtering. See Application and Implementation about negative output voltage protection for
hard shorts on battery to ground or battery reverse connection by adding small resistor.
20
Input supply, diode OR from adapter or battery voltage. Use 10-Ω resistor and 1-µF capacitor to ground as low-pass
filter to limit inrush current.
7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) ⁽¹⁾
MIN
MAX
UNIT
SRN, SRP, ACN, ACP, CMSRC, VCC
–0.3
30
PHASE
–2
30
ACDET, SDA, SCL, LODRV, REGN, IOUT, ILIM, ACOK
–0.3
7
Voltage
BTST, HIDRV, ACDRV, BATDRV
LODRV (2% duty cycle)
–0.3
36
V
–4
7
HIDVR (2% duty cycle)
–4
36
PHASE (2% duty cycle)
–4
30
Maximum difference voltage
SRP–SRN, ACP–ACN
–0.5
0.5
Junction temperature, T_J
Storage temperature, T_stg
–40
155
°C
–55
155
°C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
4
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