I finally managed to get the HWS TECs working on the superluminescent diodes. The problem was that the trimpots on the LDTC0520 drivers were not set correctly. Per page 11 of the manual, for a SLED with a thermistor and a TEC, we use trimpot LIM_A to set the cooling current limit and LIM_B to set the heating current limit.

• I added 10 full clockwise turns to SLED1/2 trimpots LIM_A/B. This allows significant control current for the TEC to flow.

The actual temperature on the SLED now goes to the set point temperature.