BQ24140_14 Datasheet, PDF (20/39 Pages) Texas Instruments – Integrated Dual-Input Switch-Mode One-Cell Li-Ion Charger with Full USB Compliance and USB-OTG Support

bq24140
SLUSAO5 – OCTOBER 2011
www.ti.com
During initial power up in default mode, the device will look at the battery voltage. If the battery voltage is less
than the V_LOWV, the device will charge the battery with a default charge current of 325mA and a default battery
charge voltage of 3.54V. The input current limit value depends on which power source was used. In the case the
bq24140 is powered up from the VIN source, the input current limit is set to 500mA. If the device is powered up
from the VBUS source, the input current limit depends on the status of the OTG pin. If the OTG pin is low, the
input current limit is set to 100mA. If the OTG pin is high, the input current limit is set to 500mA.
INPUT POWER SOURCE PRIORITY
When two power supplies are detected in default mode, the bq24140 will default to VIN operation and the VBUS
input will go to high impedance. There is a blanking time between switching from one power source to the other
power source of 10ms (t_HANDOFF). The state diagram below describes the operation (Figure 19).
Input Power Source Switch Over State Diagram
VBUS Charging Active
No
VIN > VUVLO?
Yes
Bad Adaptor Detection
for VIN
No
VIN Adaptor
Good?
Yes
Set /CE bit (B2, Register 1,
0x6b) high
Delay THANDOFF
10 ms
Start VIN Charging
Figure 19. Input power source selection in default mode
In the case where the bq24140 is in host mode, power priority will be dictated by the Host by setting one input to
high impedance and activating the other input using the HZ_MODE bit of the control register.
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