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. 

Setup:

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,

Alex.