BQ25703A Datasheet, PDF (55/81 Pages) Texas Instruments – I2C Multi-Chemistry Battery Buck-Boost Charge Controller With System Power Monitor and Processor Hot Monitor

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bq25703A
SLUSCU1 – MAY 2017
REG0x35[7] to 1)
2. Set 0x00[2] to 0 to disable LDO mode.
3. Set 0x30[0] to 0 to disable auto-wakeup mode.
4. Check if battery voltage is properly programmed (REG0x05/04)
5. Set pre-charge/charge current (REG0x03/02)
6. Put the device out of HIZ mode. (Release ILIM_HIZ from ground and set REG0x35[7]=0).
In order to prevent any accidental SW mistakes, the host sets low input current limit (a few hundred milliamps)
when device is out of HIZ.
8.6.6 Input Current and Input Voltage Registers for Dynamic Power Management
The charger supports Dynamic Power Management (DPM). Normally, the input power source provides power for
the system load or to charge the battery. When the input current exceeds the input current setting, or the input
voltage falls below the input voltage setting, the charger decreases the charge current to provide priority to the
system load. As the system current rises, the available charge current drops accordingly toward zero. If the
system load keeps increasing after the charge current drops down to zero, the system voltage starts to drop. As
the system voltage drops below the battery voltage, the battery will discharge to supply the heavy system load.
8.6.6.1 Input Current Registers
To set the maximum input current limit, write a 16-bit IIN_HOST register command (REG0x0F/0E()) using the
data format listed in Table 29 and Table 30. When using a 10-mΩ sense resistor, the charger provides an input-
current limit range of 50 mA to 6400 mA, with 50-mA resolution. The default current limit is 3.3 A. Due to the
USB current setting requirement, the register setting specifies the maximum current instead of the typical current.
Upon adapter removal, the input current limit is reset to the default value of 3.3 A. The register offset is 50 mA.
With code 0, the input current limit is 50 mA.
The ACP and ACN pins are used to sense R_AC with the default value of 10 mΩ. However, resistors of other
values can also be used. For a larger sense resistor, a larger sense voltage is given and a higher regulation
accuracy, but at the expense of higher conduction loss.
Instead of using the internal DPM loop, the user can build up an external input current regulation loop and have
the feedback signal on the ILIM_HIZ pin.
V_{ILIM _ HIZ} = 1V + 40 ´ (V_ACP - V_ACN ) = 1+ 40 ´ I_DPM ´ R_AC
(2)
In order to disable ILIM_HIZ pin, the host can write to 0x32[7] to disable ILIM_HIZ pin, or pull ILIM_HIZ pin above
4.0 V.
Copyright © 2017, Texas Instruments Incorporated
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