TPS767-Q1: output delay of 3.3V and 1.8V

Elec Cheng

Part Number: TPS767-Q1
Other Parts Discussed in Thread: DS90UB921-Q1EVM, TLV840-Q1, TPS767

Hi Expert,

I see TPS767D318PWP is used for supplying DS90UB921AS-Q1 in its reference design. You can see the TPS767D318PWP part as below. As required, the 3.3V cannot be applied earlier than 1.8V. In this design, I don't see the delay part. So how could it guarantee 3.3V will not be applied earlier than 1.8V, since the delay on circuit is random?

Thanks for your support!

BR,

Elec Cheng

over 2 years ago

0 Stephen Ziel over 2 years ago

TI__Mastermind 32560 points

Hi Elec,

I do not see a specific delay for the 2 different voltage rails in this schematic either. I'm sending this question to the owners of the DS90UB921-Q1EVM who can assist further.

Thanks,

Stephen

+1 Casey McCrea over 2 years ago in reply to Stephen Ziel

TI__Guru** 100995 points

Hello Stephen,

The 921 EVM is set up by default for 3.3V VDDIO where the supplies ramp together. For VDDIO 1.8V the best solution to ensure robustness of the design would be to control the ramps to ensure VDDIO comes up before VDD33. You could do this by connecting the 2EN pin to a supervisor IC such as TLV840-Q1 so that once VDDIO ramps, it can enable the 2EN output with 3.3V or you can use two separate converter ICs. TPS767 is just an example

Best Regards,

Casey

0 Elec Cheng over 2 years ago in reply to Casey McCrea

TI__Expert 7055 points

Hi Casey,

Thanks for your reply!

BR,

Elec Cheng

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TPS767-Q1: output delay of 3.3V and 1.8V