BQ24314C Datasheet, PDF (10/26 Pages) Texas Instruments – Li+ Charger Front-End Protection IC

bq24314C
SLUSAV3A – AUGUST 2012 – REVISED JULY 2015
www.ti.com
7.4 Device Functional Modes
7.4.1 OPERATION Mode
The device continuously monitors the input voltage, the input current, and the battery voltage. As long as the
input voltage is less than VOVP, the output voltage tracks the input voltage (less the drop caused by RDSON of
Q1). During fault conditions, the internal FET is turned off and the output is isolated from the input source.
7.4.2 POWER-DOWN Mode
The device remains in POWER-DOWN mode when the input voltage at the IN pin is below the undervoltage
threshold UVLO. The FET Q1 connected between IN and OUT pins is off, and the status output, FAULT, is set to
Hi-Z. See Figure 9.
7.4.3 POWER-ON RESET Mode
The device resets when the input voltage at the IN pin exceeds the UVLO threshold. All internal counters and
other circuit blocks are reset. The IC then waits for duration t_DGL(PGOOD) for the input voltage to stabilize. If, after
t_DGL(PGOOD), the input voltage and battery voltage are safe, FET Q1 is turned ON. The device has a soft-start
feature to control the inrush current. The soft-start minimizes the ringing at the input (the ringing occurs because
the parasitic inductance of the adapter cable and the input bypass capacitor form a resonant circuit). Figure 13
shows the power-up behavior of the device. Because of the deglitch time at power-on, if the input voltage rises
rapidly to beyond the OVP threshold, the device will not switch on at all, instead it will go into protection mode
and indicate a fault on the FAULT pin, as shown in Figure 14.
10
Submit Documentation Feedback
Product Folder Links: bq24314C
Copyright © 2012–2015, Texas Instruments Incorporated