transformer coupled logic isolator

Dec 30, 2021 Last reply: 2 years ago 24 Replies

Lots of pulse transformers have center taps, I tried to think of something that utilized a CT in some way maybe driving from the not-Q output but nothing that seemed a particular improvement on the original circuit came to mind.

I like the nice cheap surface-mount dual inductors, the DRQ74 types. No CT. They have near zero leakage inductance.

These larger-value duals they call digital audio isolators but I used to use them for a number of things including NTSC video isolation, which using current drive into a ~$2-in-singles fast LTC voltage FB op amp and then a CFA as a driver had surprisingly good performance for the parts cost.

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Naturally hard to get a hold of now, arg

Near zero leakage inductance but gobs of capacitance!

piglet

They are very nice parts, DRQ74 to DRQ127, but of course you have to understand them to use them. A lot of parts are annoying that way.

They make cool HV power supplies. I like using one as a flyboost (drive the ct in flyback mode and get 2x out) followed by a C-W multiplier.

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