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| BQ24314 Datasheet, PDF (8/13 Pages) Texas Instruments – OVERVOLTAGE AND OVERCURRENT PROTECTION IC AND Li+ CHARGER FRONT-END PROTECTION IC | |||
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bq24314
bq24316
SLUS763 â JULY 2007
www.ti.com
POWER-ON RESET
The device resets when the input voltage at the IN pin exceeds the UVLO threshold. All internal counters and
other circuit blocks are reset.
OPERATION
The device continuously monitors the input voltage, the input current, and the battery voltage.
Input Overvoltage Protection
If the input voltage rises above VOVP, the internal FET is turned off, removing power from the circuit. The FAULT
pin is driven low. When the input voltage returns below VOVP â VHYS-OVP (but is still above VUVLO), the FET is
turned on again after a deglitch time of tON(OVP) to ensure that the input supply has stabilized.
Input Overcurrent Protection
The overcurrent threshold is programmed by a resistor RILIM connected from the ILIM pin to VSS. The
overcurrent threshold is given by IOCP = KILIM ÷ RILIM.
If the load current tries to exceed the IOCP threshold, the device limits the current for a blanking duration of
tBLANK(OCP). If the load current returns to less than IOCP before tBLANK(OCP) times out, the device continues to
operate. However, if the overcurrent situation persists for tBLANK(OCP), the FET is turned off for a duration of
tON(OCP), and the FAULT pin is driven low. The FET is then turned on again after tON(OCP) and the current is
monitored all over again. Each time an OCP fault occurs, an internal counter is incremented. If 15 OCP faults
occur in one charge cycle, the FET is turned off permanently. The counter is cleared either by removing and
re-applying input power, or by disabling and re-enabling the device with the CE pin.
Battery Overvoltage Protection
The battery overvoltage threshold BVOVP is internally set to 4.35V. If the battery voltage exceeds the BVOVP
threshold, the FET is turned off, and the FAULT pin is driven low. The FET is turned back on once the battery
voltage drops to BVOVP â VHYS-BOVP. Each time a battery overvoltage fault occurs, an internal counter is
incremented. If 15 such faults occur in one charge cycle, the FET is turned off permanently. The counter is
cleared either by removing and re-applying input power, or by disabling and re-enabling the device with the CE
pin.
THERMAL PROTECTION
If the junction temperature of the device exceeds TJ(OFF), the FET is turned off, and the FAULT pin is driven low.
The FET is turned back on when the junction temperature falls below TJ(OFF) â TJ(OFF-HYS).
8
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Product Folder Link(s): bq24314 bq24316
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