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I am looking for a chip that could handle DPDT (or SPDT, or ultimately SPST) analog switch for audio routing (in the mOhm range resistance) and can guarantee one state when there is no power supply.

DPDT example

I have been looking around in manufacturer portfolios and results were those two cases :

  • Either High-impedance is guaranteed on power-off (between both NC/COM and NO/COM)

  • Or the state of the switch can't be predicted in no supply mode

So both of those cases don't guarantee one specific state in no supply mode.

Do you know any component that could suit my needs ? Thanks in advance

chillyjee
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    They are called electro-mechanical relays. Solid-state switches use active components and pretty much always need some form of power to do this. Only way to do what you want is with a) MEMS b) depletion-type FETs c) floating-gate devices. I don't know if any of the above can achieve the required few mΩ on-resistance you need (heck, even power fets tend to not pull that of...) – Joren Vaes Aug 17 '17 at 08:02
  • Why not just supply power to it? – Jason Han Aug 17 '17 at 09:35
  • Why do you think need such a low on resistance? The 14689's typical figure is 250mOhm, that's way more than "a few". – Finbarr Aug 17 '17 at 10:28
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    @JasonHan To be a little more precise I want to make an USB to jack adapter. In normal function the usb transports D+ D- and Vdd/gnd. When the jack adapter is plugged, no more Vdd and the analog audio should go directly to the headphones sound drivers by using the D+/D- of the cable as SpeakerLeft/SpeakerRight. – chillyjee Aug 17 '17 at 14:25
  • @Finbarr The lowest impedance the best because there is no amplifier for this analog audio signal before reaching the speakers, but indeed I didn't express myself accurately so "in the mOhm range" would be appropriate for this purpose. – chillyjee Aug 17 '17 at 14:25
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    "I want to make an USB to jack adapter". To connect what to what, exactly? The signals on a USB port are completely different to audio, either at line level or speaker level. – Finbarr Aug 17 '17 at 15:22
  • If you do it prior to the power stage, you could use JFETs. – Peter Smith Aug 17 '17 at 16:52
  • @Finbarr I am designing digital headphones from USB to DAC to speakers. I want to let the possibility to use them with a USB to jack adapter by bypassing the DAC and letting the signal directly reach the speakers. Hence the component I'm looking for would be placed on the digital headphones circuit board and would be either in one state when usb power is present or the other state when jack adapter is used (no usb power). – chillyjee Aug 17 '17 at 17:30
  • @PeterSmith JFETs have a too high Rds(on) impedance for my purpose. I was looking into P-channel MOSFET and found some interesting components such as the Vishay Si8481DB but all small package P-MOSFETs I could find were with the body diode with also disqualify my purpose. – chillyjee Aug 18 '17 at 09:33
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    @Finbarr Remember those USB to PS2 mouse adapters? I gather chillyjee wants to do something like that. A mouse with two plugs would be impractical so instead they make a physical-layer adapter from one to the other, that tells the mouse to switch modes. – user253751 Aug 28 '17 at 01:20
  • "High-impedance is guaranteed on power-off" Which product is that exactly? :) – endolith Aug 31 '18 at 15:13

2 Answers2

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Have a look at MAX14589E. It guarantees the switches are in OFF state when there is no supply.

https://www.maximintegrated.com/en/products/analog/analog-switches-multiplexers/MAX14589E.html

Maxim FAE
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Might be a bit late for this but you could use bistable latching relays like the TE IM41TS for example. That one is DPDT.

You can send a pulse to the coil to set or reset the state of the contacts and they'll latch until they receive another pulse with reverse polarity. That way you can save some power since you aren't constantly drawing current thru the coil to keep it on.

Avid Pro Tool
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