TMS320F28069: 97 pin output unexpected high level with power on.

Anka Zhang

Tool/software:

Hi expert,

28069's pin 97 without any connection outputs a 3.3V high level for 30ms when powered on. How can this high level be avoided?

An 11k resistor is connected to ground externally, and the voltage level is 2V.

An 2k resistor is connected to ground externally, and the voltage level is 1.3V.

As below waveform, yellow is VDDIO, bule is pin97.

No connection:

Connect 11k:

Connect 2k:

Best Regards

Anka Zhang

over 1 year ago

0 Peter Luong over 1 year ago

TI__Mastermind 25031 points

Hi Anka,

I don't see any mention of this in the errata. Can you replicate this across different F28069 devices?

Can you try using stronger pull down? What is this pin being connected to that this high pulse needs to be avoided?

Regards,

Peter

0 Anka Zhang over 1 year ago in reply to Peter Luong

TI__Intellectual 2215 points

Hi Peter,

Yes every device have this issue. What do you mean by stronger pull down? Can you tried to test and give me a solution?

Please refer to the Schematic as below:

Best Regards

Anka

0 Peter Luong over 1 year ago in reply to Anka Zhang

TI__Mastermind 25031 points

Hi Anka,

I don't have access to F28069 currently, let me ask around for a board to test this

Regards,

Peter

0 Peter Luong over 1 year ago in reply to Peter Luong

TI__Mastermind 25031 points

Hi Anka,

For this device, seems it is necessary to use other GPIO that doesn't exhibit this behavior if you need to route to driver. This GPIO can be used for other GPIO where high signal doesn't impact board such as communication

Regards,

Peter

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TMS320F28069: 97 pin output unexpected high level with power on.