The ARM JTAG opto isolator can be connected between an ARM JTAG in-circuit debugger and programmer (e.g. J-Link) and any hardware that uses the standard 20-pin JTAG connector to provide electrical isolation.

Isolating the JTAG debugger from the target board is essential whenever both are connected to different Grounds or when working with line voltage. Isolation also is useful to protect the development tools from electrical spikes.

High-speed optocouplers are used to achieve a throughput of 4 Mbit/s to minimize the impact on debugging or programming speed.

Power supply on both sides, target and emulator, are totally isolated and separately powered. The target side draws power from pins 1 or 2; the emulator side draws power from pin 19.

Note: On most ARM JTAG devices, pin 19 is a no-connect. The Segger J-Link ARM debugger can be configured to provide power via pin 19. If you are using an ARM JTAG other than the Segger J-Link ARM, double-check that you can supply +5V via pin 19 of the emulator side connector without damaging your JTAG debugger! Use at your own risk!

Download Opto-Isolator for ARM JTAG devices User's manual.