| Electronics > Projects, Designs, and Technical Stuff |
| Low-leakage triac or solid-state relay |
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| CodyDowling:
Hello, I am looking for a SSR (or triac, since I don't need isolation) that has very low leakage (~nA's or, preferably, pA's) voltage requirement is low ( >50V), and current carrying capability is low (>1A-ish). The key care about is leakage and capacitance presented to the isolated circuit (<5pF either from input to output or from input to ground). I was looking at RF SSR (https://www.digikey.com/product-detail/en/panasonic-electric-works/AQY212FG2SX/255-3866-1-ND/3885576):which is pretty good but, of course, pretty pricey. Has anyone come across something like what I'm describing? Digikey doesn't give me the ability to filter on leakage or capacitance, so I'm having to crack open and search the data sheet for each one and, so far, no dice. Thanks in advance! Cody |
| Zero999:
That's what I would have suggested. You could use a photovoltaic opto-isolator, such as the VOM1271T and two external MOSFETs, but that won't save you any money. EDIT: Here are some cheaper alternatives: https://www2.mouser.com/ProductDetail/Panasonic-Industrial-Devices/APV2121SZ?qs=sGAEpiMZZMsAwfxLaIqwNwEEjpYKNg2Ndv3wF62dBks%3d https://www2.mouser.com/ProductDetail/Panasonic-Industrial-Devices/APV2111V?qs=sGAEpiMZZMsAwfxLaIqwN8mKK5OKu01PlBRJ6K3A0lk%3d |
| CodyDowling:
Thanks for the help Hero999! On those below, it seems that the short circuit current they list in the data sheets found in links you sent below has more to do with the current "eaten" by the control circuit when the device is fully on, and not the current carrying capability- is that correct? They show a forward current of 1A, for instance, but short circuit current in the microamps... In any case, the triac seems like a natural fit, but they have even less information regarding parasitic capacitance presented to the isolated circuit than do the SSR. For the SSR, I took a guess that something labeled for "RF" would be a bit more careful with stray capacitance, but I don't see a "RF" sort parameter on the triacs. It seems that, if one didn't need to have the optical isolation, one could maybe "roll their own", right? I was thinking a couple of series mosfets (with low Ciss Coss specs) similar to a bi-directional switch for battery charging circuits, figure out how to drive the gates, and "Bob's your Auntie"... right? |
| NiHaoMike:
Depending on how low is "low voltage" and "low current", an analog switch might be the solution. |
| Kasper:
Its too bad digikey doesn't offer that as a filter option. I have typed "ctrl-f quiesc" in way too many datasheets. |
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