ADN8835 is in the digital PID mode. Heating works 9...12 seconds only.

Good day,

ADN8835 is in the digital PID mode. Heating (positive current via load) works 9...12 seconds only. 


1 Chopper1 is unused.

2. IN2N and OUT2 are connected together (shorted).

3. Control voltage from DAC ( 0V) is applied to IN2P. 

4. VTEC pin voltage shows about 4.6V (less than limit, ITEC pin shows appropriate current ~1A for my load) for 9...12 seconds after setting 0V on the IN2N pin.

5. after fews seconds (9..12 sec) VTEC and ITEC are shows near zero ( ~0.128V, 0mA).

I can set up negative voltage (-4.7 to ~0) but I can not setup positive. I can set negative voltage for a long time but I can not set up positive voltage longer than few seconds (about 10 sec). Chip is not hot but it looks like termo protection works.

I can setup positive voltage on the load for a few seconds only after power on. It is impossible to set up positive voltage if adn8835 disable it once, but i can setup negative.

Can You explain such a behavior? Is it possible to fix it?

Thanks and regards,