TEC-Drive v2

Sadly TEC-Drive v1 died an untimely death when it overheated due to being powered from +/-15 V instead of the designed +/-5 V.

TEC-Drive v2 is a simplified design using TO-220 packaged LM317/LM337 adjustable regulators and the OPA569 high-current op-amp.


Constant-current drive is achieved using the OPA569 (U2) I_monitor output. I_monitor sources/sinks a fraction I_out/475 of the actual output current. By using another op-amp (U1) in a transimpedance configuration we get a feedback-voltage proportional to the output current.

PCB layout on a 100 mm x 160 mm eurocard:



Built and assembled as a plug-in card for a 3U rack. Note big heatsinks on the +/-2.5 V regulators.


The DC-response is I_out = 105 mA/V * V_in, with an offset at zero-input of -4 mA.


With no low-pass capacitors (C1 at the input, and C11 over the transimpedance-resistor) added and a purely resistive load the frequency response extends beyond 1 MHz with some ringing.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.