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Charging a USB host in OTG mode

Sreedev K25
Intellectual 345 points
Other Parts Discussed in Thread: TSU6111

Hi,

This is a general usb question and was wondering if TI would have any products to solve the issue. Basically I'm looking for a way to charge the USB host in a USB-OTG setup. Basically I have a camera which has support for external USB mic. I want to use the external MIC and charge at the same time using a power bank. The camera has to support OTG since it' acting as the host when the mic is connected and as a slave device when connected to a computer for data transfer. On lots of googling, I came across Accessory Charging Adapter which let's you charge the host device in an OTG setup. As far as I understand it is basically inserting a resistor between the ID pin and GND instead of direct connection to GND. But I couldn't find any such adapter I can buy on the web. So I was wondering if TI would have any solutions using which I could build one on my own. I'm also aware that even if I get the hardware right, the software on the cam might not allow what I'm trying to do.

So basically, I'm trying to use a USB microphone and charge the cam at the same time.

Edit: After a bit of searching and reading USB battery charging spec 1.2 I came to understand that Accessory Charging Adapter is what I need. Does TI have any products to do the same.

Thanks and Regards.

  • 0
    TI__Intellectual 1365 points
    I guess “Basically I'm looking for a way to charge the USB host in a USB-OTG setup” means that Host (ex)Microprocessor) charges OTG device(External MIC) because Host has to furnish 5V.
    ID pin should be connected to Gnd to be a OTG device and Host(Microprocessor) should have dual-role capability(Host has a capability to have 15kohm PD resistor on D+/D- and slave has to have 1.5kohm PU resistor on either D+/D-). OTG cable or device has ID pin connected to Gnd.
    Host has to control the charger IC or Boost (5V output) to support USB OTG function. It means that you need software work to implement OTG.
    TSU6111 has a feature to support BC1.2 and OTG function.

    Here is the normal procedure to implement OTG function.

    1. OTG device is plugged in micro-USB connector
    2. TSU6111 detects OTG device through ID detection (ID pin is connected from floating to GND)
    3. TSU6111 sends interrupt signal to Host (Microprocessor)
    4. Host reads the register map to see which accessory is detected(ADC reports 0ohm PD resistor)
    5. Host control charger IC to furnish 5V output to VBUS. (Charger is Boost mode)
    6. OTG device starts operation because 5V is supplied from Host
    7. Host and OTG device starts communication