SLYT834 March   2023 ISOUSB211

 

  1. 1 Introduction
  2. 2 Existing implementation of OTG USB applications
  3. 3  On-the-go operation
  4. 4 Implementation of isolated OTG
  5. 5 Demonstration of OTG with ISOUSB211 EVM
  6. 6 Scenario A: Isolated OTG module connected to a USB-drive (bus-powered)
  7. 7  Scenario B: Isolated OTG module connected to a laptop (host)
  8. 8 Demonstration
  9. 9 Connect phone to laptop
  10. 10Connect phone to USB-drive
  11. 11Summary

6 Scenario A: Isolated OTG module connected to a USB-drive (bus-powered)

ID pin connected to the isolated OTG module (A-device) is shorted to ground. This information is sent across the isolation barrier through the reverse channel of ISO6721. The OTG module then signals VBUSON to go high, which in turn controls the switch to turn on, providing power to the flash drive (B-device). Until this stage V2OK is held low, and the OTG module does not initiate D+/D- pull-up control. Once the device side is powered up, the V2OK goes high, allowing the OTG module to control the pull-ups as per the USB2.0 standard.