TLV809: Does TLV809 not generate RESET pulse when 0.6us VDD glitch?

Kazuya Nakai59

Guru 20060 points

Part Number: TLV809

Hello guys,

One of our customers wants to know whether TLV809 generates /RESET　signal or not when VDD glitch less than 0.6us is input.

According to Figure 7 in the device datasheet (SLVSA03D), TLV809 needs 0.6us pulse width of VDD glitch at least to ensure /RESET pulse genaration. But the customer wants to know the glitch pulse width to ensure no /RESET output. If the pulse width is less than 0.3us, /RESET pulse is not generated absolutely?

Or is it difficult to guarantee the pulse width of VDD glitch to not generate /RESET signal?

Your reply would be much appreciated.

Best regards,

Kazuya Nakai.

over 6 years ago

0 Michael_DeSando over 6 years ago

TI__Genius 12630 points

Kazuya,

The way the spec is defined, and what we can garauntee, is that a pulse width of at least 3us is required at VDD for the /RESET to go active. If a pulse width of 3us or longer comes in on VDD, /RESET should trigger in all operating conditions.

-Michael

0 Kazuya Nakai59 over 6 years ago in reply to Michael_DeSando

Guru 20060 points

Michael,

Thank you for your reply. Could I ask you an additional question? If VDD glitch pulse width is less than 0.5us, whether do you think /RESET is triggered or not? Is the pulse width between 0us and 0.6us when glitch voltage is VDD-0.6V marginal level?

Thank you again and best regards,
Kazuya Nakai.

0 Michael_DeSando over 6 years ago in reply to Kazuya Nakai59

TI__Genius 12630 points

Kazuya,

If pulse width is less than 3us, we can not guarantee the /RESET will trigger. To answer your question, I don't think a pulse of 0.6us will trigger /RESET. I think 0.6us pulse width will be ignored.

-Michael

0 kai klaas69 over 6 years ago in reply to Michael_DeSando

Guru 140200 points

Hi Kazuya,

that glitches of less than 0.6µs do not trigger the reset signal is intended! This is kind of a noise suppression. This makes sense in many cases, because these fast glitches do not present a true undervoltage situation but only noise. The glitch is so short, that the usual decoupling measures can filter it out, so that there's no need to reset the whole system.

If you don't want this "noise suppression", which the datasheet calls "Vdd transient rejection", then you must choose another reset chip.

Kai

0 Kazuya Nakai59 over 6 years ago in reply to Michael_DeSando

Guru 20060 points

Michael,

Thank you very much for your reply. It's very helpful.

Best regards,
Kazuya Nakai.

0 Kazuya Nakai59 over 6 years ago in reply to kai klaas69

Guru 20060 points

Hi Kai,

Thank you very much. your reply is very helpful!

Best regards,
Kazuya Nakai.

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TLV809: Does TLV809 not generate RESET pulse when 0.6us VDD glitch?