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DRV8873S-Q1EVM: "No Power" error message and no function with DRV8873S - "Motor Control Tool"

Part Number: DRV8873S-Q1EVM
Other Parts Discussed in Thread: DRV8873, DRV8412

Hello,

i have a big problem with a new DRV8873S-Q1EVM kit.

It worked correctly for half an hour then i testet it with undervolt and motor block and now it is defekt.

The modul  is powered from a "LABORATORY DC POWER SUPPLIES" with 15VDC and max. 3A current control. The Motor takes 1.5A at block at 15VDC.

At first test all function was normaly, motor moves forward and backward at any speed.

Than i testet it with undervoltage 4V and with blockt motor at 15VDC and 1.5A.

After this test the modul don't work anymore. I messured the 15VDC on Pin13/20 at DRV8873S, 15VDC are ok.

Messured 3,3V at MSP430 and 5V at FT232RL are also correct. I can connect via serial over USB and get the Motor control window working.

On the motor control window all faults show red and under "Fault Status" on the upper right side it shows "No Power"

The "CLEAR FAULT" Button don't work and all Faults stay on red.

I messured the voltage at pin 1 "DVDD" on the DRV8873S-Chip and there are only 0.683V

Is it possible to kill the DRV8873S with 15V and 1.5A  without any heat or is there an other issue for my problem?

PS: STATUS LED is blinking normaly, VM-Led lights and nFAULT flickers some times.

  • Update:
    The problem come first on friday 16. and i switched of the powersource and disconeccted the USB-cable over the weekend.
    The board was 60 hours without power.
    Today on monday 19. i switched on the powersource and connected the USB-cable again and the problem is still there.
    No motor movement all faults are activ and it shows "No Power"
    The DVDD voltage is still at 0.683V same as on friday. I take 5VDC from a extern source and contact it to the DVDD pin of DRV8873S. The error message "No Power" disappears an the motor is working normal. Then i disconnect the extern 5VDC from the DVDD pin and the 0.683V are now raise to correct 5VDC without extern connection. Since the moment i give 5VDC from extern to DVDD for a short time the board works absolute normal without problems.
    Is it possible that the board latch without powersource and without USB-Connection for 3 days and with a 5VDC puls to DVDD it will awake and works correct? We will use the DRV8873S for a new machine with bigger production quantity but now, i am a bit confused.
    Is this a knowing problem with DVDD break down?
  • Hi Holger,

    We have not observed this failure.

    Can you provide some additional information? We would like to attempt to duplicate your finding here.
    1) Can you provide a photo of the EVM?
    2) Can you provide a detailed description of how you tested the under voltage?
    a) What are the register and EVM configuration settings?
    b) How was the load configured?
    c) What are the duty cycle settings?
    d) Did you change the power supply limit?
    e) Did you stall the motor while it was running or at motor start?
    f) What are the motor parameters (we may not have an exact motor match but can use a L/R load since it is stalled)?
    3) What is the current from the 5VDC supply when connected to DVDD?
  • Hello Rick,
    thank you for your fast reply.
    i will try to answer your questions and give you a chronological sight of the problem and the reason why the EVM looks so bad now ;-)
    Friday 16th
    - download the "DRV8873S - Motor Control" software and connected a little motor (12V 1,5A 12 Ohm) and a power supply 15V max. 3A to the EVM. Everything works fine, motorcontroll back and forward was ok. No special parameters.
    - try to go down with the supply until motor goes off, this was happens at 5VDC. No problem.
    - go back to 15VDC and blocked the running motor, the current gauge shows about 1,5A and i noticed no problem.
    - after this, i have no motor movement without blocked motor and the software shows all fault status in red and under "FAULT STATUS" it shows message "No Power" Until this moment i don't change any parameter an do no soldering on the EVM. I don't know the exact moment where the problem appears, i think it was after the motor blocking?!
    - measured the VM voltage 15V and 3,3V ok, but the DVDD at Pin1 from DVR8873S was only 0,683VDC and not 5VDC
    - weekend :-) (switched off power supply and disconnected USB-Port) EVM is complete disconnected over weekend!
    - monday morning 19th switched on power supply 15VDC and connected USB, started EVM Software. All faults are red and error message "No Power" comes back. DVDD have exactly 0,683V same as friday.
    - first idea was "mosfet Q1 problem" and i try to remove the mosfet with a little bit of heat and replaced it with a wire.
    This do not solved the problem (DVDD 0,683V) but now i got a "slack joint" at H1. If i joggle a little bit on the wiring at H1 the VM-led begin to flicker. I got a problem with the throug hole contacting of the +-pin from H1 block. I don't know if this problem exist befor or not, but the throug hole connecting is defective now. I de-soldered the H1 block and soldered it directly to the + and Gnd to the trace pads on EVM. it looks a little bad but the "slack joint" is repaired. But DVDD is still at 0,683V and no motor function.
    - Next try was to directly give extern 5V DC to the DVDD pin, "work or die" but i have no other idea what i can do. I take the 5V output from my "LABORATORY DC POWER SUPPLIES" same as the 15VDC come from. The 5V output is a L7805 Regulator with 1 A. I connected the 5VDC to DVDD, 15VDC and USB are also connected. At this moment the "No Power" message disappears and all fault messages goes to green and the motor is moving with the sliders back and forward like my first test.
    - Removed the 5V from DVDD and the Voltage on DVDD-pin is now at 5VDC, the intern regulator now works fine without extern help.
    - Since this moment the EVM works without problems, it is very mysterious.
    - removed zero Ohm resistor R30 and R32 because i will test the motor and DRV8873S with our controller but with the SPI change from TI software. This works very well, i can controll the motor from our Controller and can set the parameter over the Ti soft. Later i will controll everything from our controller.

    Can you provide some additional information? We would like to attempt to duplicate your finding here.
    1) Can you provide a photo of the EVM? > over private message
    2) Can you provide a detailed description of how you tested the under voltage? > see my post
    a) What are the register and EVM configuration settings? > until problem occurs "factory settings"
    b) How was the load configured? > PWM little motor 55mm long 35mm diameter 12V 12 Ohm 1,5A at 15VDC
    c) What are the duty cycle settings? > 100% at block moment
    d) Did you change the power supply limit? > EVM = factory, extern is 15V 3A current limited
    e) Did you stall the motor while it was running or at motor start? > it think it was while running
    f) What are the motor parameters (we may not have an exact motor match but can use a L/R load since it is stalled)?
    > Johnson "Hobby-Motor" (only for testing, not for the later product) Diameter 35mm, lenght 55mm messured 12 Ohm
    stall current at 15VDC is 1,5A
    3) What is the current from the 5VDC supply when connected to DVDD? > from L7805 max. 1A

    Hope this helps.
    I will try to get the fault back, until now it works perfectly.

    Holger
  • Hello Rick,

    now i have a brand new DRV8873 EVM  and after a minor change, i have the same problem as with my first EVM. (See first post in this thread.)

    At first test it works normal. I removed the two Zero Ohm resistors R30 and R32 to connect my own controller to PWM1 and PWM2 with 3,3V Output PWM-signal.

    From this moment the EVM don't work anymore. Error: "Under voltage fault" and DVDD Pin 1 of DRV8873 shows only 1,15V and not the correct 5V.

    See my first post in this thread, it is the same problem but at this time it does not help to give extern 5V to DVDD, the DRV8873 is dead.

    If i give 5V extern to Pin1 DVDD the DRV8873 gets hot and the DRV8873 draw 0.8A on DVDD from extern source.

    The only thing i do after first test is to remove R30 and R32 and give extern 3,3V PWM to IN1 and IN2 with removed R30 and R32.

    i think, the DRV8873 ore the EVM Boards have a massive problem, this can't be normal.

    Greetings from Germany

    Holger

  • Hi Holger,

    Sorry to hear you are having more problems.

    This sounds like it may be a different problem. I will try to duplicate your results here.

    Can you provide a few details on the connections?
    1) Was a ground connected between your controller and the EVM?
    2) Is external controller a mcu or pulse generator?
    a) If pulse generator, did you check the output voltage? I have incorrectly set the pulse generators in the past and received pulses 2x the voltage (either 0 to 6.6V or -3.3 to +3.3V).
  • Hello Rick,
    i think it is the same problem, first one 0,683V on DVDD now 1,15V on DVDD-Pin sounds like a voltage regulator problem!

    My answer to your questions:

    Can you provide a few details on the connections?
    1) Was a ground connected between your controller and the EVM?      Yes, Controller Ground was connected to EVM Ground
    2) Is external controller a mcu or pulse generator?        It is a 3,3V Controller 32bit with 3,3V PWM messured with Osci.
    a) If pulse generator, did you check the output voltage? I have incorrectly set the pulse generators in the past and received pulses 2x the voltage (either 0 to 6.6V or -3.3 to +3.3V). Controller with PWM 3,3V 20khz

    Holger Wagner

  • Hi Holger,

    Thank you for the details. Sorry, I hit send too soon.

    After removing the resistors and connecting your controller, what steps were performed on the GUI?
    What were the GUI settings?
    PH/EN or PWM mode?
    Slew Rate?
    Register settings?
    From your description, the EVM was working properly (the DRV8873 was awake and ready to receive the PWM pulses) until you issued the PWM pulses? Is that correct?

    Any other details/insights that you can provide will be very helpful.
  • Hi Rick,

    thank you for your fast response.

    Answer to your questions:

    After removing the resistors and connecting your controller, what steps were performed on the GUI?

    First it works with my controller and pwm but my "PID Motor Control" was to soft.. I tested it with different Slew Rate in your soft from 2.6 V/μs rise time to 53.2 V/μs rise time.

    This works for a short time, than i got the Fault Status on your soft "Under Voltage Fault". This fault can't be cleared and the DVDD regulator from DRV8873 is dead. (1.15V)

    What were the GUI settings? PH/EN or PWM mode? Slew Rate? Register settings?

    Operating Mode: PWM

    Slew Rate: Tested different, but after this the DRV8873 was dead

    Register Settings: I don't change anything in the Register, it was a brand new board and i only tested differnt Slew Rate on PWM Mode over your GUI


    From your description, the EVM was working properly (the DRV8873 was awake and ready to receive the PWM pulses) until you issued the PWM pulses? Is that correct?

    It work with the intern TI-Controller with the Slider from your GUI.

    It work with my Controller in PWM-Mode and PID-Soft with R30 and R32 removed

    I changed the Slew Rate to fast and different value and after this, the intern regulator in DRV8873 was dead.

    Now, the nFault LED (red) is on, the fault can not be cleared and DVDD shows 1.15V

    VBAT is connected to 12V DC from a Laboratory Power Supply with max. 3A current output and the little motor takes only 1.5A at stall (blocked)

    I have tested a lot of time with your DRV8412 and DRV8432  with same motor and with a 24V 5A Motor without any problems, but the cheaper DRV8873 will be strong enough for our concept.

    But with this problems, the DRV8873 won't be an option for our machines. Sorry.

    If you need other facts, please ask again.

    Holger