TMS320F28375S: Power Sequencing of VDDIO and VDDA

kiran kumar5

Part Number: TMS320F28375S

Hi,

In the controller datasheet (SPRS881G), section 5.9.1.2. It was given that "The 3.3-V supplies should be powered up together and kept within 0.3 V of each other during functional operation".

In our custom board, the supplies are generated from two different switcher IC's and there is a delay of 5mS between VDDA and VDDIO.

Although I'm not having any issue, will this cause a problem to the controller?

Regards

Kiran

over 5 years ago

0 Marlyn Rosales Castaneda20 over 5 years ago

TI__Mastermind 25180 points

Hi Kiran,

For your application, how often do you expect to power cycle the device?

Best Regards,

Marlyn

0 kiran kumar5 over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 50 points

Hi Marlyn,

Thanks for reply. We expect 10 to 15 power cycles per day.

Best Regards,

Kiran

0 Marlyn Rosales Castaneda20 over 5 years ago in reply to kiran kumar5

TI__Mastermind 25180 points

Kiran,

There is not enough data for us to say that you will be 100% okay long term with a 5ms delay between VDDIO and VDDA during power up. I would recommend reducing the amount of times you power cycle if you cannot minimize the delay to reduce the risk.

Best Regards,

Marlyn

0 kiran kumar5 over 5 years ago in reply to Marlyn Rosales Castaneda20

Prodigy 50 points

Hi Marlyn,

So there will be an issue in long term, ok we'll try to reduce the delay.

But is it necessary to always use a single switcher for both VDDIO and VDDA, like the one used in TI launch pad with an Inductor in between VDDA and VDDIO?

Best Regards

Kiran

0 Marlyn Rosales Castaneda20 over 5 years ago in reply to kiran kumar5

TI__Mastermind 25180 points

Kiran,

It is not completely necessary, but having only a single switcher for both VDDIO and VDDA is best practice as it will likely lead to a cleaner power rail. This is especially important if you are doing anything with the ADC, but depends on your application.

Best,

Marlyn

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TMS320F28375S: Power Sequencing of VDDIO and VDDA