| Electronics > Beginners |
| Help to identify Programmable Timer IC |
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| aju11:
I am looking for a programmable timer/counter IC which will generate a digital output (high/low) after the programmed time has elapsed. Monostable Multivibrator. Programmable time range = 5 to 15 minutes. I do not want to use 555 because since the time is large, values of R and C will be large and value of C degrades over years. I am looking for a solution similar to TPL5xxx nano timer series by TI. (but without micro-controller). And with minimum component count. Any suggestions? |
| Moriambar:
--- Quote from: aju11 on March 04, 2019, 11:58:29 am ---I am looking for a programmable timer/counter IC which will generate a digital output (high/low) after the programmed time has elapsed. Monostable Multivibrator. Programmable time range = 5 to 15 minutes. I do not want to use 555 because since the time is large, values of R and C will be large and value of C degrades over years. I am looking for a solution similar to TPL5xxx nano timer series by TI. (but without micro-controller). And with minimum component count. Any suggestions? --- End quote --- If you have a copy of the art of electronics at hand, they explain how to use an LTC6991 oscillator, with a logic gate, in order to obtain 1 hour of power. The idea behind it is to cut the output after half the cycle is complete. Unfortunately I have not the copy right here, but it's in the monostable multivibrator chapter. It's called "one hour of power". Similar ideas are featured in the LTC6995 datasheet. I think they're worth taking a look. Unfortunately I don't know any better and personally I've used the LTC6991 solution for a ~20 minutes solution in my design |
| Zero999:
The modern way to do this is to use an 8-bit micro-controller, such as the PIC12F508, PIC10F200, ATTINY9-TS8R etc. If you don't want a microcontroller then there are counter+oscillator ICs such as the CD4536, CD4541 and ICM7242. There might be a day when the above are no longer available so why not use a microcontroller? They're cheap, the programmers are widely available and using the built-in RC oscillator will give a better accuracy than an astable with an external resistor and capacitor. I could write an assembly program for a programmable delay of 5 minutes to 15 minutes using the PIC12F509, fairly quickly, even though I've not done it in years. |
| Benta:
MC14536/CD4536. Cheapest and easiest to find. |
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