CD14538B: No Spec's provided at VDD=3V

Paul Moore

Part Number: CD14538B

The CD14538B data sheet claims that VDD may be as low as 3V, but no specifications are provided at that operating voltage.
Please send the electrical specifications for operating the CD14538B with VDD = 3V

Thank you.

over 4 years ago

0 Anthony Viviano over 4 years ago

TI__Prodigy 460 points

Hi Paul,

The CD4000 technology family is best suited for 15V operation. In the case of a 3V supply I recommend using either the SN74LV221A or the SN74LV123A.

Thanks,

Anthony

0 Paul Moore over 4 years ago

Prodigy 100 points

Anthony,

The data sheet says VDD=3V is within the operating range of the CD14538B.

My question is, what are the spec's at this value of VDD.

I'm not looking for alternate parts yet.

Thank you for your help.

-Paul

0 Clemens Ladisch over 4 years ago in reply to Paul Moore

Guru 294230 points

There are no specs. While at VDD = 3 V, this device is guaranteed to work correctly, none of the electrical characteristics are guaranteed.

0 Paul Moore over 4 years ago in reply to Clemens Ladisch

Prodigy 100 points

Clemens,

The part is guaranteed to work correctly at VDD=3V.

I just need the exact definition of "work correctly".

Is the data sheet wrong in claiming use at VDD=3V?

-Paul

+1 Anthony Viviano over 4 years ago in reply to Paul Moore

TI__Prodigy 460 points

Hi Paul,

This is not an error in the datasheet, the device will function correctly at Vdd= 3V. To estimate specific parameters that are not directly listed in the datasheet I recommend using the linear interpolation method. The FAQ What method is best used for estimating specification values between those given in the datasheet is a good resource and includes excel file examples.

Please keep in mind that these CD4000 devices are optimized for 15V use case and the datasheet provides specifications at 5V, 10V, and 15V so these extrapolations will get less accurate at low voltages, but as these are worst case values they should still provide a good indication of device performance. With that said, I still recommend either the SN74LV221A or the SN74LV123A as better performance options for this 3V use case.

Thanks,

Anthony

0 Clemens Ladisch over 4 years ago in reply to Paul Moore

Guru 294230 points

"Work correctly" means that the outputs will react correctly to the trigger and reset inputs.

Interpolation does not work because there is no specification for any voltage below 3 V. Extrapolation is unlikely to work because 3 V is near the threshold voltage of the internal transistors.

0 Paul Moore over 4 years ago in reply to Anthony Viviano

Prodigy 100 points

Thank you Anthony and Clemens.

I will see what comes out of extrapolation from the 5V/10V data down to 3V.

If not good, I will see about changing the design to use the '221 or '123.

-Paul

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CD14538B: No Spec's provided at VDD=3V