BQ24295 Datasheet, PDF (25/45 Pages) Texas Instruments – I2C Controlled 3A Single Cell USB Charger

bq24295
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SLUSBC1 – SEPTEMBER 2013
When the battery charging is disabled or terminated, the system is always regulated at 150mV above the
minimum system voltage setting. The status register REG08[0] goes high when the system is in minimum system
voltage regulation.
4.5
4.3
4.1
SYS _3.9
(V)
3.7
Charge Enabled
Charge Disabled
3.5
Minimum System Voltage
3.3
3.1
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3
BAT (V)
Figure 24. V(SYS) vs V(BAT)
Dynamic Power Management
To meet maximum current limit in USB spec and avoid over loading the adapter, the device features Dynamic
Power Management (DPM), which continuously monitors the input current and input voltage.
When input source is over-loaded, either the current exceeds the input current limit (REG00[2:0]) or the voltage
falls below the input voltage limit (REG00[6:3]). The device then reduces the charge current until the input current
falls below the input current limit and the input voltage rises above the input voltage limit.
When the charge current is reduced to zero, but the input source is still overloaded, the system voltage starts to
drop. Once the system voltage falls below the battery voltage, the device automatically enters the supplement
mode where the BATFET turns on and battery starts discharging so that the system is supported from both the
input source and battery.
During DPM mode (either VINDPM or IINDPM), the status register REG08[3] will go high.
Figure 25 shows the DPM response with 5V/1.2A adapter, 3.2V battery, 2.0A charge current and 3.4V minimum
system voltage setting.
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