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RE: DRV8323: Default register settings not correct using SPI interface

October 3, 2017, 3:13 pm
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Hi Chris,

Can you confirm a few items?

1) Is the ENABLE pin set to a logic high? Based on the scope capture it appears to be.
2) How fast are you running the SPI?
3) What is the pullup value on SDO?
4) Can you capture SDO with a scope instead of a logic analyzer?
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DRV8323: Default register settings not correct using SPI interface

October 3, 2017, 1:51 pm
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Part Number: DRV8323

Good afternoon,

I have a custom TMS28027F using the DRV8323S motor driver chip, but I'm not seeing the expected response when reading the initial register settings. For instance, in the image below, during DRV initialization in lab01b, the 28027F sends a read SPI command for register 0x03h, but the response is empty. (Note that we've made custom modifications to drv8301 for drv8323 chipset). I can see the the DRV chip pulls the SPI MISO line low, but based on the manual, I expect to see non-zero initial register settings. Did I misunderstand the register settings in the manual or is there an error in my SPI communication setup?

Thanks for your support!

Best regards,

Chris

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RE: DRV8313: input the SPWM signal generated by PCA9685 to DRV8313，the output signal glitch。

October 3, 2017, 4:53 pm
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DRV8313: input the SPWM signal generated by PCA9685 to DRV8313，the output signal glitch。

October 2, 2017, 9:32 pm
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Part Number: DRV8313

I use a PCA9685 generate 3 SPWM signals，when don`t connect PCA9685 pwm output to DRV8313,the Waveform of the signal is good。But after connected,there are lot of glitch in the waveform.Why this happen?

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DRV8701: Output impedance of SO pin

October 3, 2017, 7:31 pm
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Part Number: DRV8701

Hi,

Could you let me know the output impedance of SO pin, please?

Best regards,
Shimizu

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CCS/BOOSTXL-DRV8320H: BOOSTXL-DRV8320H Code Modification Questions

September 29, 2017, 8:08 am
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Part Number: BOOSTXL-DRV8320H

Tool/software: Code Composer Studio

I am posting some questions regarding modifications to the BOOSTXL-DRV8320H code. Some have been answered already and I am posting the answers as well for future reference. Some questions still need answering. 

  1. Can it operate independent of the GUI?

    1. Yes, if you apply inputs to the gate driver yourself and ignore the Launchpad.

  2. Can it be modified to read a potentiometer for speed control?

    1. The potentiometer input is tied to the MCU but not used in the software today. So you can use it for this purpose if you write your own code.

  3. One parameter of the GUI is the number of poles in the motor. Is it a problem if I don’t know the number? The motor still functioned on the “8” pole setting.

  1. This is so that the GUI can tell you the motor RPM. If you don’t know, then the RPM readout isn’t accurate.

  • What sort of inputs do I provide independent of the MCU in order to use this without the GUI?
  • Could I make modifications to utilize the GUI for initial setup and parameter changes and then switch over to a stand-alone operation?

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RE: DRV8800: Getting Vbb on both motor terminals V+ and V-

October 4, 2017, 8:27 am
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Hi Mitja,

If you have not done so, please disconnect the motor and check the outputs with no load.

Can you provide what you are observing in the form of a logic table? Please provide all input values, including the NC pin.
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DRV8800: Getting Vbb on both motor terminals V+ and V-

October 4, 2017, 7:13 am
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Part Number: DRV8800

Hello,

I would really appreciate some help. So I've connected DRV8800 driver by datasheet, but no matter how I connect pins nSleep, Enable, Mode or Phase, I always get Vbb on both motor terminals. I double checked the wiring and is okay. In datasheet the only possible scenairo is if the motor is in brake method.  I've tried all combinations but it doesnt work. This is now the second DRV8800 that's causing me the same problem.

It is kinda frustrating so any help would be very appreciated! :)

Regards,

Mitja

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RE: DRV8323: Default register settings not correct using SPI interface

October 4, 2017, 8:46 am
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CPU is TMS320F28027F. DRV8323 enable is pulled high. SPI is 4Mhz clock. 1K pullup on SDO. Attached signals with SDO on scope. It seems to be happy today. Expected data <0x3f> returned from register Gate Drive HS, at address 0x03. We will attempt to determine why it wasn't working yesterday.

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RE: DRV8323: Default register settings not correct using SPI interface

October 4, 2017, 9:02 am
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RE: DRV8323: Default register settings not correct using SPI interface

October 4, 2017, 9:12 am
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Hi James,

We are glad to hear it is working today, and are interested to know why it did not yesterday. Please let us know what you find.

Yes this is a documentation error that will be corrected. We will check to determine which default is correct and reply soon.
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RE: DRV10983EVM: Motor Cutoff

October 4, 2017, 11:12 am
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Hello Noah,

Can you confirm if the motor tries to restart some time later with your current settings? If so, can you go to the display tab of the GUI and monitor the fault that is occuring? Do this by using the manual refresh button in the display section after the motor cuts off (If you refresh again, the fault will clear because the register is clear on read). My guess is that it will be Abnormal BEMF, however I would like to confirm it.

If the fault is Abnormal BEMF, can you tell me how you acquired the Kt of the motor? (i.e. VCC/maximum speed or Ep*Te)

Best,

-Cole

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DRV10983EVM: Motor Cutoff

October 4, 2017, 7:38 am
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Part Number: DRV10983EVM

Hello,

 

I am using the DRV10983 EVM to drive the Maxon 200188 BLDC motor. I am able to successfully drive and control the Runtian ZWL12 motor provided with the EVM, however I am unable to get the 20018 to spin properly. The 200188 begins to spin up but cutoffs before reaching the Open Loop to Closed Loop threshold. Below is a capture of the current waveform through the V phase (recommended by the Tuning guide) and captures of the values entered in the GUI:

Do you have any recommendations for a solution to this problem or what may be causing the issue? Thank you!

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RE: DRV10970: DRV10970 and DRV8308/DRV8307 Comparison

October 4, 2017, 4:22 pm
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Hey Jim,

I'm an applications engineer for the DRV10x products and I can say that the DRV8307/8 are gate drivers (in which they drive external FETs) where the DRV10970 is a driver (has the FETs integrated into the chip). I don't know about the DRV8307, but the DRV8308 and the DRV10970 can drive with 180 degree commutation to maximize torque and has the 3 Hall sensor setup like you require. Also, they both have the same protection.

Essentially, this comes down to you wanting integrated solution versus non-integrated solution (for FETs). I'd look into your requirements: board size, a voltage range, RDS on, and how much current you need for the application. Looking at the motor datasheet should help you answer these if you haven't thought about them.

I'll let a DRV8x expert speak about the differences between the DRV8307 and DRV8308.

Hope this helps,

-Cole

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RE: DRV10970: DRV10970 and DRV8308/DRV8307 Comparison

October 4, 2017, 4:31 pm
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Thanks for the quick response Cole.

Looking at the DRV8308 eval board, the RDSon is about 25 mOhm (HS + LS) with the CSD88537 FETs, but the RDSon isn't the real culprit in my application since I have a relatively low motor current (~125mA). The issue is switching losses, so I am more concerned about the switching time of the DRV10970, which is mostly dictated by the gate drive strength and the gate charge of the internal FETs, but that information is not available on the datasheet. Can you provide any additional information about the switching time, gate drive strength and/or gate charge of the DRV10970?

Thanks,
Jim
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RE: DRV8701: Output impedance of SO pin

October 4, 2017, 4:43 pm
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Hi Shimizu-san,

The output impedance will vary depending on the load.

From section 7.3.4 of the datasheet:

The SO pin can source up to 5 mA of current. If the pin is shorted to GND, or if a higher-current load is driven by this pin, the output acts as a constant-current source. The output voltage is not representative of the H-bridge current in this state.
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RE: DRV8308: Uprated DRV8308

October 4, 2017, 4:46 pm
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DRV8308: Uprated DRV8308

October 4, 2017, 1:59 pm
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Part Number: DRV8308

Hello,

How would I find out if the DRV8308 can be uprated to a higher temperature range or potentially to Automotive qualification?

Thank you,

Jim

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RE: DRV8323: Default register settings not correct using SPI interface

October 4, 2017, 4:50 pm
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Hi James,

We can confirm the dead time bits are 2'b01 as shown in the "OCP Control Field Descriptions". The "00b" above will be corrected.
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RE: DRV10970: DRV10970 and DRV8308/DRV8307 Comparison

October 4, 2017, 5:03 pm
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Hi Jim,

The DRV8308 can be forced to use 3-Hall Commutation by setting the BASIC bit.
As Cole mentioned, the DRV8308 is a gate driver allowing you to optimize the FETs for your needs. Also the voltage range is higher (32V recommended maximum vs 18V for the DRV10970).
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