Category: Hardware
Product Number: LTC1923
Hi everyone,
I’m working on a temperature control system using the LTC1923 to drive a TEC integrated inside the LDM21 laser diode module (Thorlabs). However, I'm encountering issues that I hope someone can help me clarify.
- Unstable temperature regulation – even though the temperature setpoint is achieved momentarily, the control loop seems to overreact, causing oscillation or overshoot.
- Very high TEC current consumption (close to or exceeding 2.2A), even under low thermal load conditions.
- The TEC seems to operate near full power (PWM duty almost 100%) continuously, as if the control loop is not settling properly.
- The LTC1923 PCB becomes very hot, especially in the area of the two output inductors, even when the thermal demand is low.
- The voltage at EAOUT seems incorrect; it fluctuates between 0.2–2V, outside the 0.5–1.5V range of the CT pin and is unstable.
Additional Info:
- I’ve used this same LTC1923 circuit to drive a different standalone TEC module before, and it worked very stably under the same configuration.
- Switch frequency is 1Mhz
- Current limit 2.2A
Schematic:
Here is waveform of ITEC testpoint :
The following is the ITEC test point waveform when using a different standalone TEC module, under which the system operated correctly and stably.
