Dear all
We are using the ISO7720F in a DC/DC converter. Mainly the switching commands for the gate drivers as well as switching feedbacks but also voltage measurement signals are passed through these digital isolators. So no need to say that this device is very crucial for us.
We did some tests with different operation points and also 3 day long high temperature test with operation. At the moment we try to do a temperature and power cycle test (PTCE) where we struggle with issues.
The test setup is as following:
One side of the DC/DC converter is supplied by an external voltage source. The DC/DC converter works in buck mode and controls the voltage of a capacity which is connected to the output. This means the converter works in idle and almost no current is flowing through the converter.
Several times we had all of a sudden voltage drop and oscillations on the supplied side (input) and resulting high currents flowing. We assume that the applied DC voltage is experiences a short circuit at least for some time which may result from wrong switching.
The question is now whether this can be related to the non-automotive digital isolator ISO7720FDW and the temperature cycle going from -40°C to 65°C. The error happens around 0°C to 10°C after only 1.5h to 7h of testing time. Power of converter is around 500W-1000W compared to 160kW nominal power.
We used earlier the Si8420BD-A-IS-Q1 and Si8620BD-B-IS but since this component is obsolete we were looking for an alternative which is in our opinion the ISO7720FQDWQ1.
Can you please also advice here if this is an appropriate alternative?
If you need any further information please let me know.
Thank you very much
Andreas Krättli
