MCT8316ZTEVM: The problem of abnormal DIR output

Jenson

Part Number: MCT8316ZTEVM

Hi Team,

I am using MCT8316ZTEVM for testing.

I found a very strange phenomenon now. I removed the R2, R6, R3, and R7 of the EVM, and then connected the DIR and BRAKE interfaces to the C2000. I want to use the pull-up and pull-down of GPIO to control DIR and BRAKE.

I can't control DIR normally, but I can control BRAKE normally. I was weird and checked. I found that when I did not add any control signal, DIR was high, which made me feel strange, because I saw that DIR was pulled down inside. I checked BRAKE again, it is low when no signal is applied, this is correct, and I can also use the GPIO port for control.

Now the other functions of the EVM are normal (the motor can be driven normally), but I cannot use the pull-up and pull-down of the GPIO to control the DIR signal (the pull-up or pull-down is always in one direction). Do you have any comments for this phenomenon? Why does DIR have a high level when no signal is applied, and it cannot be controlled by GPIO?

Thanks！

Jenson.

over 4 years ago

0 Matt Hein over 4 years ago

TI__Mastermind 21805 points

Hi Jenson,

Can you confirm R16 is not populated and R17 is populated? These components MUX between the DIR and nSCS signals.

Thanks,

Matt

0 Jenson over 4 years ago in reply to Matt Hein

TI__Intellectual 2465 points

Hi Matt,

Yes,R17 is 0ohm resistor is used, R16 is not connected.This is the default configuration of the EVM board, I did not change it

Thanks

Jenson

0 Jenson over 4 years ago in reply to Matt Hein

TI__Intellectual 2465 points

Hi Matt,

I found that when I re-energized nfault, DIR became low,and can use GPIO to control.I’m very curious what the reason is, it will make DIR pull up.Do you have any comments on this？

Jenson

0 Matt Hein over 4 years ago in reply to Jenson

TI__Mastermind 21805 points

Hi Jenson,

Can you try removing all jumpers from J6 to completely remove the MSP430 MCU from the circuit?

How did you "re-energize" nFAULT?

Thanks,

Matt

0 Jenson over 4 years ago in reply to Matt Hein

TI__Intellectual 2465 points

Hi Matt,

In fact, I have already done this. FG signal will be input to C2000, PWM signal is provided by C2000, nfault signal I use 3.3v output from C2000 for connection. The other jumpers are not connected

Thanks

Jenson

0 Matt Hein over 4 years ago in reply to Jenson

TI__Mastermind 21805 points

Hi Jenson,

I think you managed to get into test mode! I am looping in Aaron to help out.

Thanks,

Matt

0 Aaron Barrera over 4 years ago in reply to Matt Hein

TI__Mastermind 26046 points

Hi Jenson,

Can you confirm if there is an internal pulldown implemented on the nFAULT pin, or what the voltage of nFAULT is upon device powerup?

It is known that an internal pulldown on nFAULT can cause a voltage divider with nFAULT's external pullup, and if the nFAULT pin is latched below <2.2V upon powerup, then Test Mode begins and can cause issues such as DIR pin not working.

Thanks,

Aaron

0 Jenson over 4 years ago in reply to Aaron Barrera

TI__Intellectual 2465 points

Hi Aaron,

I use the 3.3V/5V C2000 output for direct power supply. However, it still happens that DIR is not controlled. Sometimes after the MCT8316ZTEVM is powered off and restarted, it can be controlled again.

May I ask if only nfault will be lower than 2.2V, will it enter the test mode (I use 5V, it may still happen that DIR is not controlled, but sometimes it can), can other methods cause this phenomenon?

Do you have any comment on this？

Thanks

Jenson

0 Aaron Barrera over 4 years ago in reply to Jenson

TI__Mastermind 26046 points

Hi Jenson,

Can you use a DMM to confirm the voltage of nFAULT upon powerup? Only method I am aware of so far is through the nFAULT pin being lower than 2.2V during power up.

This is all on the EVM, right? Can you share the connections from the C2000 output into the EVM? And did you modify the EVM settings in any way?

Thanks,
Aaron

0 Jenson over 4 years ago in reply to Aaron Barrera

TI__Intellectual 2465 points

Hi Aaron

Thank you for your help. I now connect the nfault pin to 5v (from C2000) and now it can perform normal control commutation. If you have any follow-up questions, I will give feedback again, thank you for your help

Jenson

0 Matt Hein over 4 years ago in reply to Jenson

TI__Mastermind 21805 points

Thanks Jenson! I will close this thread! Please click the button that says "This resolved my issue"

Thanks,

Matt

Motor drivers

Motor drivers forum

MCT8316ZTEVM: The problem of abnormal DIR output