bq24160, bq24161
bq24163, bq24168
SLUSAO0A –NOVEMBER 2011–REVISED MARCH 2012
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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 VIN_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 27 shows the
VIN–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.
Adapter Voltage Falls due
V
IN
5 V Adapter
rated for 750 mA
to Adapter Current Limit
Input Current Reduced by VINDPM function
to Prevent Adapter from Crashing
I
IN
V
SYS
750 mA Charging
750 mA Charging
I
BAT
Supplement Mode
1.2 A Load Step
I
SYS
Figure 27. bq24160 VIN-DPM
Bad Source Detection
When a source is connected to IN or USB, the bq2416x 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 (VBADSOURCE < VSUPPLY < VOVP),
the buck converter starts up and normal operation continues. If the supply voltage falls below VBAD_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
VBAD_SOURCE, the bq2416x 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.
If two supplies are connected, the supply with precedence is checked first. If the supply detection fails once, the
device switches to the other supply for two seconds and then retries. This allows the priority supply to settle if the
connection was jittery or the supply ramp was too slow to pass detection. If the priority supply fails the detection
a second time, it is locked out and lower priority supply is used. Once the bad supply is locked out, it remains
locked out until the supply voltage falls below UVLO. This prevents continuously switching between a weak
supply and a good supply.
24
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