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J-Link Target Supply Adapter

The J-Link Target Supply Adapter provides an adjustable supply voltage to the target board.



General information

The J-Link Target Supply Adapter provides an adjustable supply voltage to the target board. It has a standard 20-pin 0.1" socket towards the J-Link debug probe and a standard 20-pin 0.1" header on the target side and can directly be inserted between the J-Link and the debug cable maintaining a 1:1 connection of all debug signals. The supply voltage to the target is provided through pin 19 of the debug cable.

The supply voltage is fixed to 3.3V and can be adjusted in the range 3.6V down to 0.8V by means of changing a single resistor on the adapter (soldering required, resistor package SMD 0805). Since the J-Link Target Supply Adapter is fed by the J-Link its current capability is limited to 400mA. Furthermore the current capability depends on the chosen target voltage. Example target voltage/output current combinations:

  • 3,6V/400mA*
  • 3,3V/400mA*(default)
  • 2,5V/300mA**
  • 1,8V/200mA**
  • 1,0V/150mA** 

* To operate the J-Link Target Supply Adapter with the battery powered Flasher Portable adjustment of an additional resistor. (SMD 1206) might be required. See block diagram for details.
** Exceeding these current values will damage the adapter. To increase maximum output current see block diagram.

The J-Link Supply Adapter is compatible with J-Link BASE, J-Link PROJ-Link ULTRA+, J-Link PLUS , Flasher Portable and Flasher ARM.


Preparing J-Link to supply power

J-Link needs to supply 5V power to the emulator side of the adapter on pin 19. In order to do this, you may have to configure J-Link once as follows:

  • Make sure that SEGGER J-Link software is installed on your machine. It can be downloaded from here
  • Start J-Link Commander, which can be found under “Start -> Programs -> SEGGER -> J-Link”
  • Enter the following command: power on perm
  • Plug in the adapter: The LED on the emulator side should now be lit.