BQ25101H_15 Datasheet, PDF (15/32 Pages) Texas Instruments – bq2510x 250-mA Single Cell Li-Ion Battery Chargers, 1-mA Termination, 75-nA Battery Leakage

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bq25100, bq25101, bq25100A, bq25100H, bq25101H, bq25100L
SLUSBV8C – AUGUST 2014 – REVISED NOVEMBER 2014
8.3 Feature Description
8.3.1 Overvoltage-Protection (OVP) – Continuously Monitored
If the input source applies an overvoltage, the pass FET, if previously on, turns off after a deglitch, t_BLK(OVP). The
timer stops counting. Once the overvoltage returns to a normal voltage, the timer and charge continues.
8.3.2 CHG Pin Indication (bq25101, bq25101H)
The charge pin has an internal open drain FET which is on (pulls down to VSS) during the first charge only
(independent of TTDM) and is turned off once the battery reaches voltage regulation and the charge current
tapers to the termination threshold set by the PRE-TERM resistor. The bq25101/01H terminates at 10% of the
programmed charge current. The charge pin is high impedance in sleep mode and OVP and returns to its
previous state once the condition is removed. Cycling input power, removing and replacing the battery, pulling
the TS pin low and releasing or entering pre-charge mode causes the CHG pin to go reset (go low if power is
good and a discharged battery is attached) and is considered the start of a first charge.
8.3.3 CHG Pin LED Pull-up Source (bq25101, bq25101H)
For host monitoring, a pull-up resistor is used between the CHG pin and the VCC of the host and for a visual
indication a resistor in series with an LED is connected between the /CHG pin and a power source. If the CHG
source is capable of exceeding 7 V, a 6.2-V zener should be used to clamp the voltage. If the source is the OUT
pin, note that as the battery changes voltage, and the brightness of the LEDs vary.
8.3.4 IN-DPM (V_IN-DPM or IN-DPM)
The IN-DPM feature is used to detect an input source voltage that is folding back (voltage dropping), reaching its
current limit due to excessive load. When the input voltage drops to the V_IN-DPM threshold the internal pass FET
starts to reduce the current until there is no further drop in voltage at the input. This would prevent a source with
voltage less than V_IN-DPM to power the out pin. This is an added safety feature that helps protect the source from
excessive loads. This feature is not applicable for bq25100A.
8.3.5 OUT
The Charger’s OUT pin provides current to the battery and to the system, if present. This IC can be used to
charge the battery plus power the system, charge just the battery or just power the system (TTDM) assuming the
loads do not exceed the available current. The OUT pin is a current limited source and is inherently protected
against shorts. If the system load ever exceeds the output programmed current threshold, the output will be
discharged unless there is sufficient capacitance or a charged battery present to supplement the excessive load.
8.3.6 ISET
An external resistor is used to Program the Output Current (10 to 250 mA) and can be used as a current monitor.
R_ISET = K_ISET ÷ I_OUT
(1)
Where:
I_OUT is the desired fast charge current;
K_ISET is a gain factor found in the electrical specification
For greater accuracy at lower currents, part of the sense FET is disabled to give better resolution. Going from
higher currents to low currents, there is hysteresis and the transition occurs around 50 mA.
The ISET resistor is short protected and will detect a resistance lower than ≉420 Ω. The detection requires at
least 50 mA of output current. If a “short” is detected, then the IC will latch off and can be reset by cycling the
power or cycling TS pin. The OUT current is internally clamped to a maximum current of 600 mA typical and is
independent of the ISET short detection circuitry.
For charge current that is below 50 mA, an extra RC circuit is recommended on ISET to acheive more stable
current signal. More detail is available in 9.1 Application Information.
Copyright © 2014, Texas Instruments Incorporated
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Product Folder Links: bq25100 bq25101 bq25100A bq25100H bq25101H bq25100L