I have a product in production, since 1997. It uses the 90S1200, SOIC-20 package.
SOIC-20 is very large, and something of a fading package in 2022.
The most common 20 pin gull wing package would be TSSOP20, but you can get some MCUs in SO16N and SO14N
The function is simple:
- wait for an input to go 0 to 1 (interrupt; wakes up the CPU)
- set an output pin
- read a 4 bit dipswitch, calculate a timer delay
- run the timer,
- reset the output pin
- go to idle mode
The reason for the sleep is to reduce power, because I am running the chip with a 4MHz ceramic resonator (PBRC-4.00AR AVX). The oscillator runs all the time though, IIRC.
Can someone recommend a cheap chip which is likely to be around for many more years, draws low power like the 90S1200 (2mA active, 0.4mA idle), runs off 5V, and isn't BGA? I am not using the EEPROM and in fact the 90S1200 had corruption issues there (1st location only, IIRC). It also needs to be easy to "get into"; I don't want something weird.
The timer calculation (shortest time delay is 100us) needs to be accurate to 1% so internal RC oscillators are marginal at best.
The 1% is interesting, that is in the ballpark of modern RC oscillators, what temperature range do you need that over, and can you accept post-assemble calibrate check ?
The trim-step on most MCUs on chip OSC, is well under 1%
Parts like Silabs EFM8BB52 are likely to be available for along time, and they have good RCOSC specs, but that part lacks a Xtal osc.
A trend these day on smallest MCUs was to drop XTAL oscillator, as the on board RC osc is good enough for UARTS, tho I see some add-back the xtal choice on 20 pin parts.
Some offer 32Khz Xtal osc and auto-calibrate the RC osc from that.
The 90S1200 needs an external reset controller and I am using one of the Seiko SOT-23 chips to do that. That costs another 30p or so, and it is silly; the CPU ought to have a robust power-on reset internally.
Most new MCU should be able to manage the POR internally.
Can someone recommend a cheap chip which is likely to be around for many more years, draws low power like the 90S1200 (2mA active, 0.4mA idle), runs off 5V, and isn't BGA?
.... It also needs to be easy to "get into"; I don't want something weird.
If TSSOP20 package is ok, you could look at the '003' pinout standard, and in that family, with English data
and a Xtal Osc, would be the
Nuvoton MS51FC0AE - stocks showing at Digikey and lcsc
I notice not everyone has the Xtal on the same pins, with that '003' pinout, but a PCB option can cover that ?
If you want to keep the older SOP20-300 package, and even layout, you could trial the older but still available AT89LP2052 ? IIRC the reset flips but the pins otherwise are the same.
STC did 2052 pinout version in their older STC12C5xx series, tho I see their upgrade to that family, the STC12H series, favours TSSOP20 and TQFP32 packages, so you can see the SOP20 fading in use.