SN74LVC16T245: Power up sequence VCCB first, VCCA second

Toshihiro Watanabe

Part Number: SN74LVC16T245
Other Parts Discussed in Thread: SN74ALVC164245, SN74AXC8T245

Hello,

Is SN74LVC16T245 no issue if VCCB side power up first then VCCA power up second. In this case, OE may be low while power up because VCCA is not power up yet.

There is a discussion of SN74ALVC164245 has power sequence limitation. This limitation doesn't fit our board and becomes issue.

Please let me confirm this.

Best regards,

Toshihiro Watanabe

over 6 years ago

0 ShreyasRao over 6 years ago

TI__Guru 62600 points

Toshihiro san,

Please confirm which device is being used in your application? Is it the SN74LVC16T245 or the SN74ALVC164245?
Not following the power recommendations given in the datasheet would not cause issues or reliability concerns for the device itself. The system level concerns need to be addressed separately, if any. As recommended , having outputs disabled and input/output grounded during power up / down is advised.

0 Toshihiro Watanabe over 6 years ago in reply to ShreyasRao

TI__Genius 10235 points

Hello ShreyasRao-san,
We saw an issue by using SN74ALVC16245 guessing the reason is not following power up sequence. This is not sure.
For avoiding this issue, we are considering SN74LVC16T245 which seem not have power up sequence.
Best regards,
Toshihiro Watanabe

0 ShreyasRao over 6 years ago in reply to Toshihiro Watanabe

TI__Guru 62600 points

Hi Toshihiro-san,

What are the voltage levels being used?

Could SN74AXC8T245 be used which are validated to have glitch free power sequencing as shown below in the app note?

www.ti.com/.../scea058a.pdf

There are no hard requirements for the power sequence for the LVC device. According to the system requirements, it can be modified as needed. I recommend to have both IO ports gnded while powering up the device.

0 Toshihiro Watanabe over 6 years ago in reply to ShreyasRao

TI__Genius 10235 points

Hello ShreyasRao-san,

Please let us discuss offline. I will share you the schematic and the issue.

Best regards,

Toshihiro Watanabe

0 ShreyasRao over 6 years ago in reply to Toshihiro Watanabe

TI__Guru 62600 points

Sure, thanks Toshihiro-san.

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SN74LVC16T245: Power up sequence VCCB first, VCCA second