non-volatile analog switch?

Is this switch wired as a circuit element or is it just read by a micro?

Luhan

How many DIP switches do you need? You can cheat and use those digital pots if you don't need too many:

If you're looking for something that functions as a switch for routing signals around even when no power is available, there are some RF SPDT switches that'll still pass a signal from one input to one output or the other with no power applied -- they use something like a MOSFET and trap charge to keep the channel around without power.

---Joel Kolstad

How about latching relays ?

Graham

If its simply for setting options for a processor, the standard solution is an eeprom.

If you want to actually use the paths through the switch as current carriers to other devices, you need to implement that with a processor, and still store the settings in the eeprom.

If there are still any parallel eproms around, you can just use one to set the control lines of a cmos switch directly.

--
Regards,

Adrian Jansen           adrianjansen at internode dot on dot net
Design Engineer         J & K Micro Systems
Microcomputer solutions for industrial control
Note reply address is invalid, convert address above to machine form.

Simplest solution. Microcontroller sets control lines on analog switches, writes data to internal eeprom, goes to sleep. On powerup, reads internal eeprom and sets control lines.

Luhan

Circuit element. The idea is to not use a micro to have them set on power on, but they must be (remotely) configurable at installation/maintenance time by attaching a progammer. I do not want a dedicated micro because that implicates software development and an extra programming operation at production time. I do not want real DIP switches because users tend to change their settings and today everything has to be software configurable anyway.

Thanks, Jenalee K.

signals

Latching relays (price?) could work but I'd have to add circuitry to read back the actual position.

Thanks, Jenalee K.

Great info, Joel. I'd thought about using digital pots but their off resistance would be too low (up to 200k). And their bandwidth is a bit limited. This appnote is a better way.

Do you have any references for those RF SPDT switches?

Thanks, Jenalee K.

Hi Jenalee,

Hmm... I thought I did, but now I'm thinking I was mistaken in how the switch actually work. I believe what I looked at was

but looking at it more closely it always assumes one state when power is removed, so it wouldn't work in your application. Sorry for the confusion.

---Joel