BQ25896: Detect USB source with OTG enabled

wenzel reichmuth

Part Number: BQ25896

Hi, when I have enabled OTG there is no USB source (5V) detection possible. When I plug in a source there is no Interrupt, !PG stays low, VBUS_STAT stays 0b111, VBUS_GD stays 0.

With OTG disabled the same source will be recognized and the system switches to charging.

Is it possible to detect the source with OTG enabled by other settings? Disabling OTG and switching to charging can be done by host.

thank you very much.

over 6 years ago

0 Jeff F over 6 years ago

TI__Guru**** 166226 points

Wenzel,

With OTG enabled, the voltage at VBUS is above the UVLO threshold and so the IC doesn't realize when a source is connected. You can try forcing DPDM detection using REG02b1 but I suspect that functionality is disabled when OTG is enabled.

0 wenzel reichmuth over 6 years ago in reply to Jeff F

Prodigy 40 points

Oh i apprehended this.

Unfortunately force DPDM does not do the Trick.
I was thinking there is a possibility to detect a slightly higher VBUS because the charger supplies 5.1V and I could set VBOOST to 4.9V or something.
Anyway, thank you for the reply!

0 wenzel reichmuth over 6 years ago in reply to Jeff F

Prodigy 40 points

Okay I've got the solution.

With ADC enabled (REG02 CONV_START/CONV_RATE) the Host can detect a connected supply by reading VBUS_GD (REG11) and then manually switch to charging by disabling OTG.

Power management

Power management forum

BQ25896: Detect USB source with OTG enabled