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CD4536B COUNTER TIMER

imtiaz khan
Intellectual 430 points
Other Parts Discussed in Thread: CD4536B, CD40106B

Dear All

I have the following questions regarding the CD4536B counter timer IC:

1) The 'CLOCK' for this IC can be made from externally connected 'R' and 'C' to appropriate pins. This part is available from one other manufacturer which gives the clock period approximately as "Tc = 2.3RC" whereas TI datasheet gives it as "Tc = 3RC". Why so much difference in the Tc value given that they are the same parts?

2) Logic diagram of this part shows Pin 3 to be a Schmitt input. However there is no mention of 'upper' and 'lower' trigger thresholds and 'hysteresis' voltages. Given this absence of information is it safe to say that they are the same as CD40106B Hex Schmitt triggger IC since both of these ICs belong to the 'B' series CMOS family?

3) From a product life cycle perspective where would be the TSSOP version of CD4536?

Questions (1) and (2) above pertain to a requirement to accurately (+/-3%) set the clock period (Tc) by installing a calculated value of 'R' +/-1% given a fixed 'C' +/-1%.

Regards

i.k

  • 0
    TI__Mastermind 46480 points

    1) The 'CLOCK' for this IC can be made from externally connected 'R' and 'C' to appropriate pins. This part is available from one other manufacturer which gives the clock period approximately as "Tc = 2.3RC" whereas TI datasheet gives it as "Tc = 3RC". Why so much difference in the Tc value given that they are the same parts? I dont know why there is so much difference. In general thes internal oscilators on thes type part are not very accurate as far as following a formula goes. The formula will get you in the ballpark and then you can tweak it in by varying the R/C values.

    2) Logic diagram of this part shows Pin 3 to be a Schmitt input. However there is no mention of 'upper' and 'lower' trigger thresholds and 'hysteresis' voltages. Given this absence of information is it safe to say that they are the same as CD40106B Hex Schmitt triggger IC since both of these ICs belong to the 'B' series CMOS family? Yes I beleive that would give a good indication. This spec should not matter unless you are using an external oscilator. The part should always work when using its own oscillator.

    3) From a product life cycle perspective where would be the TSSOP version of CD4536?  Our standard Logic and linear products do not get obsoleted as long as there are any sales at all.  We dont have life cycles.

    Questions (1) and (2) above pertain to a requirement to accurately (+/-3%) set the clock period (Tc) by installing a calculated value of 'R' +/-1% given a fixed 'C' +/-1%

    Once the oscilator frequency is set it is very accurate as far as stability and drift but the formula to calculate the frequency using the R/C values is about +/- 25%