SN74LVC1T45: The input to SN74LVC1T45DCKR is in between high and low

Danilo A.

Part Number: SN74LVC1T45
Other Parts Discussed in Thread: TLV7011, SN74LVC1G17, TLV4041

Hi Team,

Our customer would like to know how much extra current (Icc) will be added when the input to SN74LVC1T45DCKR is in between high and low and if it is okay to keep the input in the middle of the supply voltage all the time.

Thank you for your support!

Regards,

Danilo

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 317370 points

Typically several milliamperes (there is no guaranteed limit):

The Δt/Δv limit must not be exceeded; see [FAQ] How does a slow or floating input affect a CMOS device?

Adding a Schmitt-trigger buffer (e.g., SN74LVC1G17) allows such signals, but does not reduce the power consumption. For truly analog signals, it would be a better idea to use a comparator (e.g., TLV7011, TLV4041).

0 Danilo A. over 4 years ago in reply to Clemens Ladisch

TI__Mastermind 28840 points

Hi Clemens,

Thank you for your response. Can you please share where the graph above came from? I just want to provide a reference document to the customer.

Thank you for your support!

Regards,

Danilo

0 Rami Mooti1 over 4 years ago in reply to Danilo A.

TI__Mastermind 35638 points

Danilo,

This can be found in the Low-Voltage Logic (LVC) Designer's Guide

This particular graph is figure 1-7 on page 1-19 (19th page of section 1) of the document, which would be the 39th overall page of the PDF.

Thanks,
Rami

0 Danilo A. over 4 years ago in reply to Rami Mooti1

TI__Mastermind 28840 points

Hi Rami and Clemens,

According to the customer the figure below indicates some hysteresis, but another figure shows oscillations. Which is the case for LVC, or is it temperature dependent?

Regards,

Danilo

0 Clemens Ladisch over 4 years ago in reply to Danilo A.

Guru 317370 points

LVC inputs have a small amount of hysteresis, but it is not enough to protect against slow signals.

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SN74LVC1T45: The input to SN74LVC1T45DCKR is in between high and low