SN74LVC157A: Input transition rise or fall rate

Nanfang Liao

Intellectual 2085 points

Part Number: SN74LVC157A

Hello team,

My customer use SN74LVC157A, and they test waveform of pin1and find Input transition rise or fall rate is 82ns/V, which is much higher than our spec 10ns/V, they want to know if this applicatioin is OK, it is risk of output? thanks

Regards,

Nanfang

over 8 years ago

0 Clemens Ladisch over 8 years ago

Guru 316860 points

The limit of 10 ns/V is for the worst case, so there is some distance from the actual limit. Furthermore, ten is a suspiciously round number.

However, there is no guarantee whatsoever. Anything beyond 10 ns/V is not OK.
The only safe way to use that signal is with a Schmitt trigger buffer.

0 Emrys Maier over 8 years ago in reply to Clemens Ladisch

TI__Guru* 97046 points

Thanks Clemens - great info, as usual.

Nanfang,

You might also find this application note helpful - it discusses the reasons why slow inputs are undesirable in CMOS devices.

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SN74LVC157A: Input transition rise or fall rate