DRV8834 Hi-z level

Jerry Chu

Other Parts Discussed in Thread: DRV8834

Hi,

DRV8834 shows some input pin has the pull low resistor around 200Kohm. But in some application, M0/M1 need to be the high impedance mode. Does the MCU need a special seting? BTW, do you have any document to suggest the motor driver circuit for avoide the EMI issue? Thanks!

over 9 years ago

0 Wilson Zuo over 9 years ago

TI__Mastermind 26065 points

Hi Jerry,

M0 pin does not have all-time internal pull down as it needs HiZ configuration. The MCU I/O interfacing with M0 should be able to be set as tri-state as High/ Low/ HiZ.

For EMI issue, Is there any specific concern of the EMI spectrum? Normally ferrite beads to the outputs pins can limit the high frequency EMI.

Best regards,

0 Jerry Chu over 9 years ago in reply to Wilson Zuo

Genius 4915 points

Hi Wilson,

My customer are using STM32F401 serial MCU, it doesn't have the Hi-Z mode at GPIO. Does open-drain could be a good choice? Thanks!

0 Wilson Zuo over 9 years ago in reply to Jerry Chu

TI__Mastermind 26065 points

Hi Jerry,

Set as "output, open-drain without pull-up or pull-down" and in an OFF state should work.
Also you can set as "input floating".

Best regards,

0 Jerry Chu over 9 years ago in reply to Wilson Zuo

Genius 4915 points

Hi Wilson,
The test is ok! But why we set the GPIO to open drain, the M0 pin got 1.5V level? Thanks!

0 Wilson Zuo over 9 years ago in reply to Jerry Chu

TI__Mastermind 26065 points

Hi Jerry,

That is expected. Because the device has weak pull up and pull down for the tri-state input pins. So that when the external input is in HiZ, there will be less impact to the internal divided voltage which just setting the dividing level at the middle level. That is how tri-state works.

Best regard,

Motor drivers

Motor drivers forum

DRV8834 Hi-z level