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

1 Introduction

USB is becoming increasingly popular as an interface in industrial systems for human-machine interactions, diagnostics, firmware downloads, connections of peripherals and data-logging. Given the presence of noise and harsh transients present in the industrial world, as well as for electrical safety, systems designers prefer to isolate the USB port. Having one USB port that can connect to both a host (such as a laptop) or a peripheral (such as a USB drive), instead of separate ports for host and peripheral connections increases flexibility and reduces costs.

USB On-the-Go (OTG) offers this flexibility, while also allowing host and peripheral roles to be swapped through Host Negotiation Protocol (HNP). However, there is no solution available currently to isolate an USB OTG port. In this article, the key considerations on implementing an isolated USB OTG port with HNP and the corresponding requirements from an isolated USB repeater are described, along with an application diagram and test results implementing Isolated USB OTG port with TI’s ISOUSB211 isolated USB repeater.