SN74AVC4T245: SN74AVC4T245 Unused input floating

Jade Goo

Intellectual 1940 points

Part Number: SN74AVC4T245

Hi Team,

My customer use only 2 channel with SN74AVC4T245.
They floating unused 2 channels A/B side both.
Datasheet recommended unused channel hold to VCC or GND.
They want to know unused pins floating is critical issue?
Thank you.

Best Regards,
Jade

over 8 years ago

0 Michael J Schultis over 8 years ago

TI__Mastermind 24975 points

Hello Jade,

Any unused inputs to a CMOS device must be held at VCC or GND, or there may be additional current consumption, which could in theory cause thermal runaway.
It would be recommended to have all unused A and B channels pulled to ground.
Please refer to the following application note for additional information:
www.ti.com/.../scba004d.pdf

Best,
Michael

0 Jade Goo over 8 years ago in reply to Michael J Schultis

TI__Intellectual 1940 points

Hi Michael,

Thank you for your feedback.
I already checked datasheet and application that you attached.
However, still I don't think floating unused pins occur critical issue during the operation.
It might be increased current consumption and increased thermal, but still no issue with operation and doesn't critical issue.
Would you let me know your opinion about my thought?
Thank you.

Best Regards,
Jade

0 Michael J Schultis over 8 years ago in reply to Jade Goo

TI__Mastermind 24975 points

Hello Jade,

It is possible that it could ultimately cause device failure due to thermal runaway. The heating of the device can cause the problem to become worse and worst until the device fails.
It is highly recommended that the inputs are grounded, as the device operation is not guaranteed otherwise.

Best,
Michael

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SN74AVC4T245: SN74AVC4T245 Unused input floating