BQ28550-R1 datasheet(12/42 Pages) TI1

12 / 42 page

Not Recommended for New Designs

bq28550-R1

SLUSAS4A – OCTOBER 2012 – REVISED SEPTEMBER 2014

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Protection (continued)

In the overcharge state, if a charger is removed and a load is connected, the external charge control MOSFET

conducts the load current through its parasitic body diode. If the VBAT voltage becomes lower than the

overcharge release voltage (VREL1 = 4.070 V typ) for a period up to the overcharge release delay time

(tREL1 = 8 ms typ), the COUT pin transitions to a high level, enabling charge of the battery by turning on the

external charge control N-channel MOSFET.

7.5.2 Over-Discharge Detector

When discharging a battery, if the VBAT voltage becomes lower than the over-discharge detection voltage

(VDET2 = 2.3 V typ) for a period up to the over-discharge detection delay time (tDET2 = 24 ms typ), the bq28550-

R1 device detects the over-discharge state of the battery, and the DOUT pin transitions to a low level. This

prohibits discharging the battery by turning off the external discharge control N-channel MOSFET.

In the over-discharge state, if a charger is connected, the external discharge control MOSFET conducts the

charge current through its parasitic body diode. If the VBAT voltage becomes greater than the over-discharge

detection voltage (VDET2 = 2.3 V typ) for a period up to the overcharge release delay time (tREL2 = 4 ms typ), the

DOUT pin transitions to a high level, enabling discharge of the battery by turning on the external discharge

control N-channel MOSFET. After detecting over-discharge, the device stops all operations and enters standby,

which reduces the current consumed by the IC to its lowest mode (standby current).

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