DRV8825: Maximum allowable voltage at Decay pin

Danilo A.

Part Number: DRV8825

Hi Team,

Our customer would like to know the maximum allowable voltage at the DECAY pin. The minimum VIH in the datasheet is 2V but there is no maximum value. Is the maximum allowable voltage at the DECAY pin equal to 7V as stated in the Absolute Maximum Ratings of the digital pin voltage at Section 7.1 of the datasheet?

Regards,

Danilo

over 3 years ago

0 Wang5577 over 3 years ago

TI__Guru 56650 points

Danilo,

The Decay pin is safe if the voltage is below 7V. The internal pull-up source is 3.3V. So, you can use a 3.3V source as the pull-up source.

0 Danilo A. over 3 years ago in reply to Wang5577

TI__Mastermind 24715 points

Hi Wang,

Thank you for the confirmation.

Regards,

Danilo

0 Danilo A. over 3 years ago in reply to Danilo A.

TI__Mastermind 24715 points

Hi Wang,

At page 28 of the User's Guide of DRV8825EVM shows that the DECAY pin can be connected to a potentiometer but it is not clear what its function is.

Regards,

Danilo

0 Ryan Kehr over 3 years ago in reply to Danilo A.

TI__Guru 54675 points

Danilo,

The DRV8825 supports 3 different decay modes. It is TTL logic. If voltage is <0.8V, Slow decay will be used. If voltage is >2V, fast decay is used. If the decay pin is floating (JP3 shunt removed completely), than mixed decay is used.

The potentiometer just allows you to change the voltage to <0.8V or >2V on the DECAY pin. A jumper could just as easily been used to connect DECAY pin directly to GND or to 3.3V.

0 Danilo A. over 3 years ago in reply to Ryan Kehr

TI__Mastermind 24715 points

Hi Ryan,

Thank you for the clarification.

Regards,

Danilo

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DRV8825: Maximum allowable voltage at Decay pin