Hello,
We're developing a board that uses a gumstix board. This contains an OMAP3530, and a tps65950 power management chip. The gumstix exposes the USB OTG signals onto an external connector which we use. The USB OTG host port from the tps65950, with ID grounded, works as expected (running linux, usb mass storage devices enumerate correctly). However, the tps65950 can only source 100mA, so any device requesting more than this is not enumerated.
We have an external 5V supply that will source 500mA, so i'd like to use this. However, i'm not clear on how to inform the host OS that it can allow through devices requesting more than 100mA in the enumeration. I'm also not clear on whether I should physically connect my external 5V supply to the VBUS pin on the tps65950? The TI document "Powering OMAPTM3 With TPS65950: Design-In Guide" rather unhelpfully merely states -
"In case there is a need to use an external 5-V supply for larger current needs then one can use an external supply; however, the VBUS pin from the device must be connected to the VBUS pad on the USB connector".
On my test board, I have the tps65950 VBUS pin connected to the VBUS pin of my USB socket, and that VBUS line is connected to my external 5V power supply. Is that correct? Devices requesting more than 100mA still don't work.
Any help with this would most appreciated.
Regards
Rob Smith