SN74HC08 / Input transition rise and fall rate

S.Satoshi

Other Parts Discussed in Thread: SN74HC08, SN74HC08-Q1

Hi,

Please let me ask about Input transition rise and fall rate of SN74HC08. There is Input transition rise and fall rate in Recommended Operating Conditions but I'm suspecting that this may be rise and fall time, not rate. Because I found following information from SN74HC08-Q1 datasheet and app note for logic IC.

SN74HC08-Q1 datasheet

http://www.ti.com/lit/ds/symlink/sn74hc08-q1.pdf

Implications of Slow or Floating CMOS Inputs (Rev. C)

http://www.ti.com/lit/an/scba004c/scba004c.pdf

Best Regards,

Sonoki

over 9 years ago

0 ShreyasRao over 9 years ago

TI__Guru 59940 points

Hi Satoshi san ,

yes , the HC/ HCT family has input transition fall /rise time and the calculation on the rate has to be derived from that . The approx. rate will be about 130ns/V for 4.5Vcc which is assuming the 10 to 90% for the rise time .

0 S.Satoshi over 9 years ago in reply to ShreyasRao

Guru 21685 points

Hi Shreyas,

Thank you for your response. I understand that the fall/rise time can be calculated from fall/rise rate. But now I'd like to know if SN74HC08 datasheet has typo and it should be below correctly.

[From SN74HC08 datasheet]

Best Regards,

Sonoki

0 ShreyasRao over 9 years ago in reply to S.Satoshi

TI__Guru 59940 points

Satoshi san ,

I agree , this needs changed to transition time .

0 S.Satoshi over 9 years ago in reply to ShreyasRao

Guru 21685 points

Hi Shreyas,

Thank you for your comment. Can you request to revise the datasheet to change this spec?

Best Regards,
Sonoki

0 ShreyasRao over 9 years ago in reply to S.Satoshi

TI__Guru 59940 points

yes , I have put in the request.

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Logic forum

SN74HC08 / Input transition rise and fall rate

http://www.ti.com/lit/ds/symlink/sn74hc08-q1.pdf

http://www.ti.com/lit/an/scba004c/scba004c.pdf