BQ25872 Datasheet, PDF (23/68 Pages) Texas Instruments – Battery Switch Charger

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bq25872
SLUSCQ6 – OCTOBER 2016
Feature Description (continued)
8.3.5.5 IBAT and VBAT Protection
The device monitors current through the battery by monitoring the voltage across the external, series battery
sense resistor. The differential voltage of this sense resistor is measured on SRP and SRN. A 10-mΩ series
resistor is recommended for battery current monitoring. A lower resistor value can be used, but it will result in
lower measurement accuracy. A higher resistor value can be used, but it will result in decreased charging
efficiency.
When the IBAT_REG threshold is reached, the device will go into LDO mode to regulate the battery current at
the IBAT_REG threshold. See LDO mode section for more details about the device operation during LDO mode.
If the IBAT_OCP threshold is reached and IBAT_OCP protection has been enabled, the battery switch will be
disabled within t_{OFF_FET} after a deglitch time of t_{IBAT_OCP} and CHG_EN is set to ‘0’. Host intervention is required to
set CHG_EN to ‘1’ to enable the battery switch again.
The device monitors battery voltage by measuring the differential voltage on BATP and BATN pins. When the
VBAT_REG threshold is reached, the device will go into LDO mode to regulate the battery voltage at the
VBAT_REG threshold. See LDO mode section for more details about the device operation during LDO mode. If
the VBAT_OVP threshold is reached and VBAT_OVP protection is enabled, the battery switch will be disabled
within t_{OFF_FET} after a deglitch time of t_{VBAT_OVP} and CHG_EN is set to ‘0’. Host intervention is required to set
CHG_EN to ‘1’ to enable the battery switch again. If the VBAT_REG or IBAT_REG value written to the register is
greater than the max defined value for the register, then the corresponding register will be set to the highest
defined value.
If a threshold has been reached (IBAT_REG, VBAT_REG, IBAT_OCP or VBAT_OVP), the appropriate bit in the
EVENT_x register is updated (set to ‘1’ if threshold is crossed, ‘0’ if threshold is not crossed). If the
EVENT_x_MASK bit is not set to ‘1’ for the corresponding bit in the EVENT_x register, then INT will assert low to
alert the host of a fault.
8.3.5.6 VOUT Protection
The device monitors voltage on VOUT when the device has a valid power supply. When the VOUT_REG
threshold is reached, the device will go into LDO mode to regulate the VOUT voltage at the VOUT_REG
threshold. See LDO mode section for more details about the device operation during LDO mode. If the
VOUT_OVP threshold is reached and VOUT_OVP protection is enabled, the battery switch will be disabled
within t_{OFF_FET} after a deglitch time of t_{VOUT_OVP} and CHG_EN is set to ‘0’. Host intervention is required to set
CHG_EN to ‘1’ to enable the battery switch again. If the VOUT_REG value written to the register is greater than
the max defined value for the register, then VOUT_REG will be set to the highest defined value for the register.
If a threshold has been reached (VOUT_REG or VOUT_OVP), the appropriate bit in the EVENT_1 register is
updated (set to ‘1’ if threshold is crossed, ‘0’ if threshold is not crossed). If the EVENT_x_MASK bit is not set to
‘1’ for the corresponding bit in the EVENT_x register, then INT will assert low to alert the host of a fault.
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