I don't see an obvious smoking gun to blame, while this shouldn't be so hard.
I repeat some of my earlier advice to consider changing around the voltage divider so DAC never sees large negative potential in any start up scenario.
JR
PS: Zener across vreg output should not be necessary, unless the spike is coming into the VREG from the output side?
DAC output help
Re: DAC output help
Cancel the "cancel culture", do not support mob hatred.
Re: DAC output help
Has this stopped breaking, or have you stopped working on it for a while?
JR
JR
Cancel the "cancel culture", do not support mob hatred.
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- Location: Oakland/Paris
Re: DAC output help
Hi - sorry I've not been visible on my own thread - busy moving from France to US.
Putting the zener diodes on the regulator outputs has eliminated the turn-on transients which seemed to be the culprit of the DAC destruction. The unit has been problem free for almost 2 months, so I'll incorporate the zeners into the final design.
I had re-orientated the bias + DAC output + filters, as we had originally discussed a long while ago to make a higher impedance between the bias feed and the DAC output, but this hadn't eliminated the problem. I had also implemented the tracking bias supply that was suggested... none of this solved the problem, so I bought a new scope, and saw the transients on the supply.
Once I incorporate the THAT1570 layout tips from member "promixe", I should have my final pcb design.
Putting the zener diodes on the regulator outputs has eliminated the turn-on transients which seemed to be the culprit of the DAC destruction. The unit has been problem free for almost 2 months, so I'll incorporate the zeners into the final design.
I had re-orientated the bias + DAC output + filters, as we had originally discussed a long while ago to make a higher impedance between the bias feed and the DAC output, but this hadn't eliminated the problem. I had also implemented the tracking bias supply that was suggested... none of this solved the problem, so I bought a new scope, and saw the transients on the supply.
Once I incorporate the THAT1570 layout tips from member "promixe", I should have my final pcb design.