SN74AHCT1G86: Input threshold max. min. levels

DENIZ GULER

Part Number: SN74AHCT1G86
Other Parts Discussed in Thread: LM393B, TLV3231, TLV1871

Tool/software:

Hello,

I'd like to use this part as an oscillator but need to know all threshold levels to see the frequency accuracy. Could you please provide all input threshold levels?

Thank you

Deniz Guler

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 324950 points

You must not use this device with slow input edges; see the t/v limit in section 5.3. Only a device with Schmitt-trigger inputs would work with slow edges.

For logic devices, the thresholds are not very well specified. If you care about accuracy, you have to use a comparator instead.

0 DENIZ GULER over 1 year ago in reply to Clemens Ladisch

Prodigy 10 points

Thank you, it is fast enough for my application. I'm looking for cost effective solutions and if the device's threshold range can be specified that greatly helps.

+1 Owen Westfall over 1 year ago in reply to DENIZ GULER

TI__Genius 15501 points

As Clemens said Logic devices thresholds are not specified during oscillations and the actual value of a threshold can shift between lots, or device updates without needing to change the value in the datasheet.

That being said this devices input thresholds are found in the recommended operating conditions section.

The actual value will be slightly lower than 2V and slightly above 0.8V, but these are the values that guarantee a transition on this device.

What was highlighted above is the output voltage levels and those values are dependent on system conditions.

Regards,

Owen

0 DENIZ GULER over 1 year ago in reply to Owen Westfall

Prodigy 10 points

Thank you for your reply, yes I should have shared this input voltage table instead of output levels. My struggle is when those threshold levels even slightly change it affects the switching frequency dramatically.

0 Clemens Ladisch over 1 year ago in reply to DENIZ GULER

Guru 324950 points

What frequency and voltage ranges do you need? The cheapest comparator would be the LM393B.

0 DENIZ GULER over 1 year ago in reply to Clemens Ladisch

Prodigy 10 points

It is 700kHz with at least 3.3V output high, to not exceed around 60ns propagation delay at transitions would be ideal.

0 Clemens Ladisch over 1 year ago in reply to DENIZ GULER

Guru 324950 points

TLV1871 or TLV3231.

Logic

Logic forum

SN74AHCT1G86: Input threshold max. min. levels