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BQ27425-G2_15 Datasheet, PDF (31/39 Pages) Texas Instruments – Fuel Gauge With Integrated Sense Resistor
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10 Power Supply Recommendations
bq27425-G2
SLUSB23B – OCTOBER 2012 – REVISED JUNE 2015
10.1 Power Supply Decoupling
The battery connection on the BAT pin is used as an input for voltage measurement of the battery. A capacitor of
value of at least 0.1 μF should be connected between BAT and VSS. The capacitor should be placed close to the
gauge IC and have short traces to both the BAT pin and VSS.
The battery connection on the REGIN pin is used to supply power to the gauge. A capacitor of value of at least
0.1 μF should be connected between REGIN and VSS. The capacitor should be placed close to the gauge IC and
have short traces to both the REGIN pin and VSS.
The fuel gauge has an integrated LDO with an output on the VCC pin of approximately 2.5 V. A capacitor of
value at least 1 μF should be connected between the VCC pin and VSS. The capacitor should be placed close to
the gauge IC and have short traces to both the VDD pin and VSS.
11 Layout
11.1 Layout Guidelines
A capacitor of at least 1 μF is connected between the VCC pin and VSS. The capacitor should be placed close to
the gauge IC and have short traces to both the VCC pin and VSS.
• A capacitor at least 0.1 μF must be connected between the BAT pin and VSS if the connection between the
battery pack and the gauge BAT pin has the potential to pick up noise. The capacitor should be placed close
to the gauge IC and have short traces to both the VDD pin and VSS.
• If the external pullup resistors on the SCL and SDA lines will be disconnected from the host during low-power
operation, TI recommends using external 1-MΩ pulldown resistors to VSS to avoid floating inputs to the I2C
engine.
• The value of the SCL and SDA pullup resistors should take into consideration the pullup voltage and the bus
capacitance.
• If the GPOUT pin is not used by the host, the pin should still be pulled up to VDD with a 4.7-kΩ or 10-kΩ
resistor.
• The BIN pin should not be shorted directly to VCC or VSS.
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