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SN74LVC245A: SN74LVC245A Power Up Behavior Issue

Part Number: SN74LVC245A

Hi Team,

My customer is using SN74LVC245A for a control logic as below.

The VCC 3V3' and VCC 3V3 are different power rails. In the customer's use case, the VCC3V3's powering up time is 320ms later than VCC 3V3.

But during the test, t was found the VCC3V3 power rail will affect the VCC3v3' power rail in the powering up status. This is something that will cause damage to customers' system in VCC3V3' side. So we'd like to learn why the VCC3V3' power rail would be affected by the VCC3V3 power rail, as DIR is already pulled up high by VCC3V3, which means direction is from A to B.

BTW, Pulling up OE to VCC3V3 would solve the issue, but as there's no control signal can be used for this OE control, so customer pull down the OE pin to the GND.