DRV8837 Output when VCC 0

Jennifer Wang

Intellectual 2065 points

Other Parts Discussed in Thread: DRV8837

Hi Motor Driver Team,

Setting this forum post up for Tyto.

"Regarding the DRV8837, I’m assuming that when VCC is 0V, the outputs are high impedance, correct? Ideally, they’d be at 0V to hold the motor in park."

Best regards,

Jennifer Wang
Texas Instruments Inc.
Technical Sales Rep

over 12 years ago

0 Nicholas Oborny over 12 years ago

TI__Mastermind 21320 points

Hi Jennifer,

I believe with no logic supply (VCC) the outputs will Hi-Z. I am double checking with the designer.

The desired behavoir will most likely vary from customer to customer. But assuming your device loses power most likely the best scenario is for the outputs to Hi-Z. An adrupt brake can be harsh on the system.

0 Rick Adolf over 12 years ago in reply to Nicholas Oborny

Intellectual 335 points

What i need to know specifically is:

What’s the maximum VCC level to guarantee that the outputs are tri-state on a 74LVC1T45? I want to use VCCA as a tri-state control (see attached schematics). i.e. if I’m driving VCC with a 74LVC device with a maximum Vol of .4V, will the 74LVC1T45 output be tri-state?

Don't worry about brake function as the nfets will only be turned after some delay after the driver chip is disabled (delay is software controllable).

Please expedite the response to this as layout needs to be completed by end of day 8/5.

0 Nicholas Oborny over 12 years ago in reply to Rick Adolf

TI__Mastermind 21320 points

Rick,

Can I see the schematic, it does not seem to be attached to your last post. Are you asking about the outputs of the DRV8837 or the 74LVC1T45? I am unsure from your question.