I'm looking for a (logic)chip with one or few bits of permanet memory, e.g.the status is saved over a power down period. If possible at all it should operate in a voltage range up to 18V (automotive application).
Many thanks for hints.
- Wilfried
A battery backed up flip-flop or 2 ?
More sensibly, use an eeprom.
Graham
Not a lot of information about what is interfaced to the bits. The simplest "memory" might be a 12 V nominal, latching relay rated for an automotive environment.
-- Rich Webb Norfolk, VA
Does it have to be solid state? Would a latching relay, or one of those twisting-solenoid pixels they use in big signage work?
There are plenty of many-kilobit memories, but they'll depend on your interface requirements.
How about a lithium battery-backed CMOS latch?
If we knew more about the intended application, or the problem you are trying to solve, we might be able to be more helpful...
You could use a microcontroller with on-board EEPROM. Or a latching relay. Or use CMOS logic with a small 'permanent' lithium battery or double-layer capacitor for backup.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Sure, a latched relay would do the job. I just have the idea to realize this simple piece of electronic in solid state. And using an eeprom (with timing circuits) would be wasting most of it.
To describe the function: Two seconds after starting the car, a (potential free) resistor has to be switched between 100 Ohm and infinite (open circuit), however, only every second time. The power used at the installation place is switched on and off with the car engine. So this is used to power the circuit and as the switch pulse. All this has to be in a very small housing, using little energy. The 100 Ohm resistor is used only for calibrating purposes, practically drawing no current. All this operated at car board power.
- Wilfried
Two seconds after turning the ignition on, activating the starter, releasing the starter, after reaching a certain number of RPMs, or something else?
What's the bias on the resistor? Can you use an analog switch?
Does the resistor return to 100 ohms when the car is turned off, or 2 seconds after the car is started the next time?
It sounds like you are trying to trick the car's computer into doing something, care to tell us what?
for simplicity 12 volt latching relay, PM maintains last position and uses a pulse.
-- Real Programmers Do things like this. http://webpages.charter.net/jamie_5
Some (many?) of the tiny one-chip CPUs include some EEPROM.
It may seem crazy to use a part that's much much bigger than you need, but that is often the cheapest solution. I remember years ago when DEC was shipping ethernet Host ID ROMs in 64K byte chips. (I might be off by a few powers of two.) They only needed
32 bytes, but that was the cheapest ROM chip they could get.-- The suespammers.org mail server is located in California. So are all my other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited commercial e-mail to my suespammers.org address or any of my other addresses. These are my opinions, not necessarily my employer's. I hate spam.
You don't by any chance mean the 2764 64k*bit* ROMs do you ?
Graham
Sounds right. Thanks. (So I was off by 3 factors of 2.)
Another example of a part that may be less expensive if you waste half of it. Consider using a whole CODEC or PC audio chip if you need either an A/D or a D/A.
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Wavefront make individual stereo A/Ds and D/As that are actually quite good. I still had to 'overspecify' when I only needed one channel of A/D conversion though ! ;~)
Graham
snipped-for-privacy@suespammers.org (Hal Murray) wrote in news:fPqdneBglvuA_R7ZnZ2dnUVZ snipped-for-privacy@megapath.net:
Can you name some parts? I might want to investigate that idea. My abilities and money usually limit me to modifying existing hardware, but that ides might be better for an accurate log converter than most of the ideas I've come up with or been told so far.
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Go to Digikey and poke CODEC into the search box. You will get hundreds of hits. You will have to wade through the data sheets to see if you can find anything that will work for your application.
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snipped-for-privacy@suespammers.org (Hal Murray) wrote in news:TfKdnbBFPaq59xvZnZ2dnUVZ snipped-for-privacy@megapath.net:
Thanks :) I'll have a look. I'm hoping something exists which has both ADC and DAC, plus a way to put a log converter program on it. I can imagine the finding of both ADC and DAC on one chip might be awkward, but hopefully not so.
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