PWM INL_C with different DTC Register

amos lin

Other Parts Discussed in Thread: BOOSTXL-DRV8301, TMS320F28027F, MOTORWARE, DRV8301

Hi all,
I am transplanting from "C2000 LaunchPad XL TMS320F28027F + BOOSTXL-DRV8301 REVB" to my board.

The attachment is my schematic and layout(with Protel 99SE).

I use MotorWare Lab3a to do adc calibration, no modify anything, no connect motor. I got some questions:

Enviroment:
Power: DC 24V
Motor: DC 24V, BLDC

Question:
Once power on, the fault is always lighting on.
I measured pwm with INL_C, it show this:

if I changed DTC resistor to 150k ohm(10, 1k, 10k, 33k, 100k... is no effect), the waveform is:

and sometimes it will be this. With DTC 150k ohm, the fault is twinkling.

Other channels have the same status.

Voltage on some test point are:
    BST_A/BST_B/BST_C               10.48V
    SHA, SHB, SHC                   0.5V
    DVDD                            3.3V
    AVDD                            6.5V
    VSENS                           0.8V
    IA_FB                           1.68V
    IB_FB                           1.67V
    IC_FB                           1.67V
    DV_V_FB                         2.98V
    GVDD                            11.0V
    CP1/CP2                         11.3V

I don't know what happens, can anyone help me?

thank you

BLDC.zip

over 9 years ago

0 Wilson Zuo over 9 years ago

TI__Mastermind 26065 points

Hi Amos,

We will check this and get back later. Have you encountered the same thing when using TMS320F28027F + BOOSTXL-DRV8301 TI boards?

Best regards,

0 amos lin over 9 years ago in reply to Wilson Zuo

Intellectual 280 points

Hi Wilson,
TI's EVM board is ok. This issue is only in my custom board.

thank you for reply.

0 Wilson Zuo over 9 years ago in reply to amos lin

TI__Mastermind 26065 points

Hi Amos,

Before anything else, could you check on the PowerPAD connection to GND? it should be well connected not only for thermal function but also for electrical.

Best regards,

0 amos lin over 9 years ago in reply to Wilson Zuo

Intellectual 280 points

Hi Wilson,

PowerPAD had well connected to GND.

thank you for reply.

0 amos lin over 9 years ago in reply to amos lin

Intellectual 280 points

hi,

I had made a new board, and find a line broke. After fixed, it has still no effect.

thank you.

0 Wilson Zuo over 9 years ago in reply to amos lin

TI__Mastermind 26065 points

Hi Amos,

That is not my first time seeing the dealing with the PowerPAD like this. But this has very big concern. Please following our datasheet and APN for the PowerPAD PCB design.

The truth is feeding solder from the back side through a big hole can only get a very small chance to get the PowerPAD really wet for the soldering. It will produce something like it "looks" connected but never real get soldered down. And the previous similar issues mostly are solved just by resoldering with hot air gun. But your case will also not able to use hot air gun as the hole is too big which can't hold the solder after using hot air gun. Please try some hand craft just make sure the PowerPAD is soldered to the GND net.

Also, I think the layout so far is need improving. Please follow the DRV8301 boostpack PCB design as much as possible.

Best regards,

0 amos lin over 9 years ago in reply to Wilson Zuo

Intellectual 280 points

Hi Wilson,

Ok, I will make a new layout follow EVM board, and the drv8301 boostpack PCB design.

Thank you for your help.

Best regards,

amos

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PWM INL_C with different DTC Register