Author Topic: Help to identify Programmable Timer IC  (Read 513 times)

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Offline aju11

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Help to identify Programmable Timer IC
« 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?

 

Offline Moriambar

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Re: Help to identify Programmable Timer IC
« Reply #1 on: March 04, 2019, 01:02:14 pm »
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?
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
« Last Edit: March 04, 2019, 01:06:02 pm by Moriambar »
 

Offline Zero999

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Re: Help to identify Programmable Timer IC
« Reply #2 on: March 04, 2019, 02:23:11 pm »
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.
 
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Offline Benta

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Re: Help to identify Programmable Timer IC
« Reply #3 on: March 04, 2019, 04:39:37 pm »
MC14536/CD4536. Cheapest and easiest to find.
 
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