SN74LVCH16T245: Power-Up Considerations

Hey Markus,

Traditionally if a part requires special power up requirements it will be mentioned in the "Power Supply Recommendations" section of the data sheet. For this part, as you're probably aware, it doesn't have any such concerns. I recommend following the guidelines that you found in the datasheet for powering this device:

For most voltage translation devices, a good thing to know is that Vcca rail will be the lower supply voltage. Since there is no mention of this you should be good to go either way but if you want to play it safe then place the lower supply voltage  on the Vcca rail. Additionally, when this Vcca <= Vccb condition exists, the supply ramps shouldn't matter, it just needs to meet that condition during operation. For future reference, always read the datasheets though since exceptions are sure to occur.

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Best Regards,

Nick

Hi Markus ,

They are recommendations from TI ,which are also given in the datasheets. Not following the recommendations 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 inputs grounded during power up / down is advised.

I've the following power-up sequence:

The 3V3 is done by a LDO. Can I say, that the 3V3 on VCCA is powered up first and after a while the 5V on VCCB is also on its level - therefore powered up second?

Or do I have to do first switch on 3V3 (like a step) and then 5V (like a step) with a certain delay between these steps? If yes how much delay?