TPS650350-Q1: For TPS65035000-Q1, why will no output if Vbuck1 get 3.3V from outside?

Jiawei Hu1

Part Number: TPS650350-Q1
Other Parts Discussed in Thread: AWRL1432

Tool/software:

Hi team,

For TPS65035000-Q1 paired with AWRL1432, we get no output if Vbuck1 output get reverse 3.3V? Is that normal? What is the reason? Thanks!

Jiawei

over 1 year ago

0 Phil Yi over 1 year ago

TI__Mastermind 49091 points

Hi Jiawei,

What do you mean "Vbuck1 output get reverse 3.3V"?

Thanks!

Phil

0 Jiawei Hu1 over 1 year ago in reply to Phil Yi

TI__Expert 5555 points

Hi Phil,

The input of TPS65035000-Q1 is 5V, Vbuck1 output is 3.3V and there is no 3.3V output if no 5V input. But if we get 3.3V at Vbuck1 output before input 5V, which leakage from somewhere else, will TPS65035000-Q1 disable output? What is the reason? Thanks!

Jiawei

0 Jiawei Hu1 over 1 year ago in reply to Jiawei Hu1

TI__Expert 5555 points

Hi Phil,

Pls help feedback today, thanks!

Jiawei

0 Phil Yi over 1 year ago in reply to Jiawei Hu1

TI__Mastermind 49091 points

Hi Jiawei,

Yes; TPS65035000-Q1 doesn't output properly; the reason is the SCG issue described as the screenshot from datasheet below:

Thanks!

Phil

0 Phil Yi over 1 year ago in reply to Phil Yi

TI__Mastermind 49091 points

Hi Jiawei,

I got answer from design copied here: It seems like SCG has to be 1 to proceed in the power sequence.

My explanation is: When VIN is applied to the device, it checks all 4 SCG bits for all 4 power rails' output, only when all 4 SCG bits are "1" which means all 4 outputs voltage level lower than 300mV (TPY), and then the PMIC starts to power on; otherwise, the PMIC stops powering on.

Thanks!

Phil

Power management

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TPS650350-Q1: For TPS65035000-Q1, why will no output if Vbuck1 get 3.3V from outside?