NRF51822: VDD = 2.4V, programming via JLink Lite

[NK]

Hi,

If I have a custom board with the NRF51822 operating at VDD=2.4V, would it be possible to program the part using Segger JLINK Lite programmer that comes with the dev-kit.

1. Can I feed in VDD (2.4V) to the VTREF pin of JLINK Lite?
2. If I understand the JLINK Lite spec correctly, the SWD_CLK signal would be driven at 3.3V level irrespective of VTREF. Would a current limiting resistor on SWD_CLK connection to NRF51822 suffice?
3. For SWD_DATA, I am guessing that having a pullup to 2.4V on board would suffice as VIH for the Segger IC is 0.6*VIF (3.3V) = 2V.

Is there a recommended circuit for interfacing JLINK Lite programmer to NRF51822 operating at 2.4V?

-NK

[bjorn-spockeli]

I think that the VTREF pin has to be fed with 3.3V.