BQ24161B_15 Datasheet, PDF (23/52 Pages) Texas Instruments – bq2416xx 2.5A, Dual-Input, Single-Cell Switched-Mode Li-Ion Battery Charger with Power Path Management and I2C Interface

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bq24160, bq24160A, bq24161
bq24161B, bq24163, bq24168
SLUSAO0F – NOVEMBER 2011 – REVISED JULY 2014
Feature Description (continued)
9.3.16 Input Voltage Protection in Charge Mode
9.3.16.1 Sleep Mode
The bq2416xx enters the low-power sleep mode if the voltage on V_SUPPLY falls below the sleep-mode entry
threshold, V_BAT+V_SLP, and V_SUPPLY is higher than the undervoltage lockout threshold, V_UVLO. This feature
prevents draining the battery during the absence of V_SUPPLY. When V_SUPPLY < V_BAT+ V_SLP, the bq2416xx turns off
the PWM converter, turns the battery FET on and drives BGATE to GND, sends a single 128μs pulse on the
STAT and INT outputs and updates the STATx and FAULT_x bits in the status registers. Once V_SUPPLY > V_BAT+
V_SLP, the STATx and FAULT_x bits are cleared and the device initiates a new charge cycle.
9.3.16.2 Input Voltage Based DPM
During normal charging process, if the input power source is not able to support the programmed or default
charging current, the supply voltage decreases. Once the supply drops to V_{IN_DPM} (default 4.2V for both inputs),
the input current limit is reduced to prevent further supply droop. When the IC enters this mode, the charge
current is lower than the set value and the DPM_STATUS bit is set (Bit 5 in Register 05H). This feature provides
IC compatibility with adapters with different current capabilities without a hardware change. Figure 15 shows the
V_IN–DPM behavior to a current-limited source. In this figure the input source has a 750mA current limit and the
charging is set to 750mA. The SYS load is then increased to 1.2A.
V_IN
5 V Adapter
rated for 750 mA
I_IN
Adapter Voltage Falls due
to Adapter Current Limit
Input Current Reduced by V_INDPM function
to Prevent Adapter from Crashing
V_SYS
750 mA Charging
I_BAT
Supplement Mode
750 mA Charging
I_SYS
1.2 A Load Step
Figure 15. bq24160 V_IN-DPM
9.3.16.3 Bad Source Detection
When a source is connected to IN or USB, the bq2416xx runs a Bad Source Detection procedure to determine if
the source is strong enough to provide some current to charge the battery. A current sink is turned on (30mA for
USB input, 75mA for the IN input) for 32ms. If the source is valid after the 32ms (V_BADSOURCE < V_SUPPLY < V_OVP),
the buck converter starts up and normal operation continues. If the supply voltage falls below V_{BAD_SOURCE} during
the detection, the current sink shuts off for two seconds and then retries, a single 128μs pulse is sent on the
STAT and INT outputs and the STATx and FAULT_x bits of the status registers and the battery/supply status
registers are updated. The detection circuits retry continuously until either a new source is connected to the other
input or a valid source is detected after the detection time. If during normal operation the source falls to
V_{BAD_SOURCE}, the bq2416xx turns off the PWM converter, turns the battery FET on, sends a single 128μs pulse is
sent on the STAT and INT outputs and the STATx and FAULT_x bits of the status registers, and the
battery/supply status registers are updated. Once a good source is detected, the STATx and FAULT_x bits are
cleared and the device returns to normal operation.
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