DRV8412DDWEVM is not working

Fang,

The corresponding ground for PWM_A and PWM_B needs to be connected to GND (not AGND, same net as Pin 13) of the DRV8412

The PWM_C and PWM_D inputs should also be connected to the same GND.

You can stop the motor either by pulling PWM_A and PWM_B both low (0V), or by asserting RESET_AB/RESET_CD.

There is a 1000uF capacitor between PVDD and GND; if there is barely any load, this capacitor discharges very slowly. It does not surprise me that it still holds some charge a day later.

Thanks,

Matt

Matt,

Thanks for your help.

But I have another doubt.

Under mode 1, PVDD is 9v after power on. If OUTA is disconnected with OUTB, the voltage between them is 9v. When they are connected together with only one resistor (2K Ohm) between them, the voltage between OUTA and OUTB is only 3.6v. I can't understand this.

Would you please tell me.

Thanks again.

Fang

Fang,

In this case, what are the inputs that you are supplying to the DRV8412?

Thanks,

Matt

Matt,

I don't really understand which inputs you are talking about, power inputs or control inputs? Anyway, here is my configuration for all operation modes.

a stable 12V power supply for GVDD,

a battery of 9V for PVDD,

GNDs on both boards are connected together,

PWMA is normally 2.4V but can be easily adjusted between 0V and 4.9V.

PWMB&C&D are grounded.

all other pins are float.

Any more information you need?

Thank you so much for your help.

Fang

Can anybody help me with this?

I just received this board from pne of TI  distributor and I am extremely anxious to get the answer or any instrution.

Really appreciate any response.

Fang

Fang,

I have a few concerns:

What PWM duty cycle are you using on PWMA?

also,

How are you measuring the output of the half bridges?

As an aside, I would highly suggest obtaining a brushed DC motor to test the output instead of a resistor.

Thanks,

Matt

Matt,

Thanks again for your response.

The PWM duty cycle is 100% so I can keep the voltage stable and measure this voltage via a multimeter. 

In one of my test, I found a ridiculos phenomenon. I have only one power (24v, let's call it Vsource), and this power is translated to 12v for PVDD, and to 5v for a potentiometer (the output voltage on this potentiometer is normally 2.4v and can be adjusted by a joystick). But before I connect the potentiometer and DRV device,

the electrostatic potential at GND corresponding to potentiometer is about 2v lower than electrostatic potential at GND on DRV device.

Can you believe this?

I don't think there should be some difference between a brushed DC motor and a resistor ( with 0.1% precision). However, I gonna do some test according to your suggestion later. 

Fang

Fang,

You cannot have a 100% duty cycle as the PWM. The bootstrap capacitors will not function properly. Try setting the cycle to something like 95%. Otherwise, I cannot guarantee the operation of the device.

Thanks,

Matt

Matt,

First, about what i said last time,

"

In one of my test, I found a ridiculos phenomenon. I have only one power (24v, let's call it Vsource), and this power is translated to 12v for PVDD, and to 5v for a potentiometer (the output voltage on thispotentiometer is normally 2.4v and can be adjusted by a joystick). But before I connect the potentiometer and DRV device,

the electrostatic potential at GND corresponding to potentiometer is about 2v lower than electrostatic potential at GND on DRV device.

"

This phenomenon might occured only once, or I might incorrectly read the voltage on the multimeter last time. Anyway, I tried several times and now "the electrostatic potential at GND corresponding to potentiometer is almost same as electrostatic potential at GND on DRV device". 

Here is the latest progress: I used one BDC and 10K Hz PWM under mode 4(other PWMs are grounded). A battery of 9v for PVDD. The duty cycle is switched from 1% to 99% or vise versa, and the voltage between OUTA and OUTB (refered to Vab henceforth) changed to opposite side correspondingly. Before I connect OUTA and OUTB to BDC, Vab is about 8v. But after I connect both OUTA and OUTB to BDC, Vab is about 4v several seconds later and continues to drop. Once I disconnect OUTA and OUTB, Vab is changed to 4v higher than before several seconds later and will slowly increase (increase speed is slower than drop speed). From this test, it seems there is a 4v drop somewhere.

It cost me more than 2 weeks to get this board from TI distributor, and I didn't get any progress on my project for almost one week. I am really going insane with these problems.

Is there any way to locate the problem ASAP? 

Thanks.

Fang

Fang,

I am curious, can you measure the battery voltage as you turn the motor on? I have had similar problems in the past when the supply voltage has dropped because of current limitations.

I am currently trying to replicate your problem on my end. Do you have a schematic for your setup?

Thanks,

Matt

Matt,

I should have paid enough attention to every word you said, especially the numbers. It is high duty cycle which caused this problem. Now I decreased the duty cycle and it works very well.

I really appreciate your patient help.

Nice Day:)

Fang

Matt,

I'm sorry I failed to close this subject. actually I haven't been able to close some subjects for a long time. I click yes to indicate one of your post is exactly the answer, and wait for completion of page refresh. The question, did this answer your question, is still there. even sometimes I tried via a proxy.

Anyway, thanks again

Fang