SN74LVC1T45-Q1: Risk on power up VCCA before VCCB

Lucas Wassenius

Intellectual 895 points

Part Number: SN74LVC1T45-Q1

Hi Team,

Customer has a design where they power on VCCA 1.8V rail before VCCB 3.3V/5V.

Datasheet mentions:

Is there any risk involved with power sequencing VCCA before VCCB?

Kind regards,

Lucas

over 1 year ago

+1 Michael Ikwuyum over 1 year ago

TI__Mastermind 22445 points

Hi Lucas,

Note that the power up sequence recommendation is to help make sure your control circuitry is supplied first and there should be no risk involved, thanks.

Best Regards,

Michael.

0 Lucas Wassenius over 1 year ago

TI__Intellectual 895 points

Hi Michael,

What could happen if you don't supply the control circuitry first?

The IC will not work anyway if not both are supplied, so I don't understand why we need this distinction.

Thanks,

Lucas

0 Michael Ikwuyum over 1 year ago in reply to Lucas Wassenius

TI__Mastermind 22445 points

Hi Lucas,

The state of the I/O pins can be undefined especially since the outputs can randomly drive either high or low during power up, thanks.

Best Regards,

Michael.

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SN74LVC1T45-Q1: Risk on power up VCCA before VCCB