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I would need a one bit permanent memory. With permanent, I mean able to maintain it value across power reset. Something like EEPROM or Flash. Ideally, something equivalent to a RS-latch.

Searching, I found several I2C EEPROM or PIC, but that would include too much complexity for my purpose. And seem a drop of resources to use a serveral-Kbits chip when only one is required.

Is there some IC for permanent (few bits) latch? If yes, what is it name so I may search for it? Any example of it?

EDITED: To clarify,I am asking for a very simple Integrated Circuit. The purpose is to include it on a PCB. As an example, 5x5mm SO/TSSOP for 0.1$ would be something acceptable.

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    \$\begingroup\$ For a single bit, you might consider a bistable latching relay. \$\endgroup\$ Jun 11, 2016 at 17:37
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    \$\begingroup\$ Yes, I was thinking of an electro-magnetic relay - a quick search at Digikey for "latching relay" finds a large variety. \$\endgroup\$ Jun 11, 2016 at 18:05
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    \$\begingroup\$ @PeterBennett: I think there is a misunderstanding: I am searching for some <5mm TSSOP IC for <0.1$, etc.. Not a huge 5$ slow electromagnetic relay. Sorry, I will clarify the question. \$\endgroup\$ Jun 11, 2016 at 18:11
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    \$\begingroup\$ It would be a waste of resources to build an entire IC with wiring pads, protection diodes, output drivers, and the whole works for just one bit. And that doesn't even get into the power regulation and timing control for programming, etc. The cost difference between a 4 bit Flash chip and a 16 kbit flash chip is probably less than 1%. \$\endgroup\$
    – Ben Voigt
    Jun 11, 2016 at 18:24
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    \$\begingroup\$ Your lowest cost option, to avoid the complexity of flash programming, would be a small capacitance to power just a very energy-efficient latch. It's not truly non-volatile, but it serves most applications. \$\endgroup\$
    – Ben Voigt
    Jun 11, 2016 at 18:26

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I would also suggest you look at a digital volume control chip (DS1669). Perhaps not common these days but popular a while back. You could ramp the attenuation up and down with an up and down digital input and it would write it to internal EEPROM when idle. It would survive power off and could be even used to store a few bits if you were to read the attenuation setting with an analogue input.

Most micros have versions with FLASH on chip so it would only require one IC.

A supercap, capacitor or button cell will keep the state of a 4000 series CMOS register stable for a LONG time.

There is a tiny FPGA IC (Lattice iCE40UL1K-SWG16) that might do the job as seen on https://hackaday.io/project/6592-dipsy but I am not sure if it can self modify.

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    \$\begingroup\$ Very interesting solution \$\endgroup\$ Jun 11, 2016 at 20:16
  • \$\begingroup\$ There are moves to develop MEMRISTOR technology that might one day work. \$\endgroup\$
    – KalleMP
    Dec 14, 2023 at 11:29
  • \$\begingroup\$ There are "Dallas" 1 wire devises that have various amounts of FLASH memory for storage and parameters. Probably needs micro to program it. \$\endgroup\$
    – KalleMP
    Dec 14, 2023 at 11:35

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