density

John Larkin · 2023-04-29T22:18:36+00:00

Somebody was whining about PCB density.I want to do a board with about 105 relays. I'd prefer 130 but that'snot going to happen.Here's a trial placement, just to see what might fit. normally use the TPIC6595 shift register as our relay drivers. Butit's big and I'd need 14 of them. So I think I'll add another TrionFPGA and have its pins drive a logic-level SOT23 mosfet under eachrelay. The T20 is only about $11, about half the cost of 14 of the TIthings.I do need to be sure that the relays won't interact magnetically.The coils will generate heat too, brickwalled like that. I think we'lluse 24 volt relays and run them at 16 volts quiescently, to cut thepower dissipation about in half. We can bump the coil voltage up to 24for a few milliseconds, whenever we change the pattern. [1]My production people think they have ideas for placing 100+ relaysefficiently.I have about 10 square inches on the right for the rest of the stuffI'll need. And there's always the bottom of the board.[1] sorta like the Austin-Healey overdrive solenoid.

Apr 29, 2023 Last reply: 3 years ago 21 Replies

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John Larkin 3 years ago

No, 10x20 mm things, SPDT, like Omron G5Q and some similar ones. Brickwalled, I'd like to make sure they don't interact.

We'll test that. Dropout time is a sensitive indicator.

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