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RE: DRV10983: calculating in/out power

July 17, 2018, 9:16 am
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Hey Viktorija,

Yes, there is a relationship between the speed command and actual speed which also relates to the power calculation.

Generally speaking, the output current (RMS) multiplied by the applied voltage (RMS) is the power. The applied voltage equation is shown below:

  • V_applied = V_CC*(%_speedCommand)

For a high level, example calculation, 100% speed command will apply V_CC (typical = 24V) and with an output current (typical 2A(RMS)): (2A)(24W) = 48W.

To build on this concept, the applied current and voltage can be called the phase current and voltage. These can be measured with an oscilloscope. So the speed command will apply some percentage of VCC in a 3rd harmonic semi-sinusoidal fashion, and the phase current is applied as a sinusoidal waveform. The RMS of both waveforms can be taken, multiplied together, and the power can be calculated for a specific speed command.

Best,

-Cole

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RE: DRV10983: DRV10983

July 17, 2018, 9:35 am
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Hello Hemantha,

Let me answer your questions below:

  • The voltage measured on VREG pin is 3.3V, how can they make it 5V for running there  controller.
  • There is a register that simply changes the value of VREG, I've copied an pasted the register map below:

  • We want I2C to communicate with DRV10983, can you please share any example code or how to communicate through I2C. Currently, We are  taking help from SLVUAA5 for using I2C communication with DRV.
  • SLVUAA5 is what I'd recommend you'd look at for programming I2C with our device
  • I've copied and pasted our section about I2C below. Generally speaking, I2C needs a device ID, the register value that will be read or written to, and the value (if writing). The pull-ups on the I2C line will determine data that are considered "1's" while "0's" as the determined by the master device (e.g. MCU) by driving the pin to GND. I believe SLVUAA5 gives examples of the waveforms in this context.

  • while tuning motor using DRV10983EVMGUI there is an error message displaying <ERR> register writing not successful.
    • Here are some things to check for this error
      • Ensure the set-up has been followed in the DRV10983 EVM User's Guide
      • Make sure the USB2ANY firmware is updated to 2.7.0.0 (using the USB2ANY explorer)
      • Make sure you have successfully download the 2014 NI labview run time engine
      • Make sure the program is run in adminstrator mode
      • Ensure the USB2ANY LED is illuminated during this entire procedure
    • Let me know if you can get the "enable configure button" to turn green. This indicates that I2C writes were successfully recieved by the device.

Best,

-Cole

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RE: DRV8881: DRV8881P (R1 and R2 value)

July 17, 2018, 10:23 am
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HI Rick,

I'm also working on the project and wanted to say that making R1 to 0 ohms makes sense, but I wanted to know if having R2 was even necessary at this point if we don't need the voltage divider. Could we remove R2 and make a straight wire from V3P3 to AVREF and BVREF or if we do need R2 what would be the value of it be, would it have to be hight like 10k ohms?  

Thank you for the help!

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RE: DRV8881: DRV8881P (R1 and R2 value)

July 17, 2018, 11:07 am
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Hi Uriel,

Yes, you can remove R2 if you want to connect directly to V3P3.

The suggestion to add footprints for both R1 and R2 allows current adjustments if necessary.

A total R1+R2 of more than 10kOhms would be good. This would minimize the external V3P3.
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RE: DRV8881: DRV8881P (R1 and R2 value)

July 17, 2018, 11:24 am
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Hi Rick,

Thank you for the help!

Regards,
Farinaz
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RE: DRV10987: Spread spectrum modulation control

July 17, 2018, 3:41 pm
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Jonathan,

I agree not what I would have expected to see. I would have expected all of the frequencies to be there but with a more rounded shape and lower peak value. Not sure what might be causing the behavior you've observed.

Could you send me your EEPROM settings (you can just save the config file and send that to me). So that I can review them.

I'll also try to duplicate the measurement that you're making on my bench.

Thanks,
Brian
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RE: TMS570LS1224: - code example for DRV3205?

July 17, 2018, 3:59 pm
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Hi Anthony,
Thanks for your replay. I am very sad this time, it will cause great losses to others for my mistake.
Thanks very much. Best wishes to you!
Alex
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RE: DRV8320: OCP trigger poin with differnt DC Bus

July 17, 2018, 8:39 pm
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Hi Rick,
customer using DRV8320H
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DRV8320: OCP trigger poin with differnt DC Bus

July 6, 2018, 2:14 am
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Part Number: DRV8320

Customer tried the OCP function with the DRV8320 without Motor loading.

1. VBUS=36V, The delay time between nFAULT pin and OCP trigger point of 52A is 2uS. With the time delay, the current goes up to 86.4A 

 2. VBUS=50V, The delay time between nFAULT pin and OCP trigger point of 52A is 3.2uS. With the time delay, the current goes up to 128A.

The delay time difference between 36V and 50V is 1.2uS (3.2uS-2uS).  How come? Is this time related to the bus voltage? Is this behavior able to be improved? Thanks.

DRV8320 setting:

OCP Setting: VOCP is set at 0.13V, (VDS pin is connected to GND thru 18KOhm)

Ext. MOSFET's Rds(on) = 0.0025R, so that the OCP trigger point is set 52A

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DRV8801A-Q1: Effects of exceeding abs. max. ratings and driving in continuous overcurrent, short-circuit

July 17, 2018, 11:41 pm
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Part Number: DRV8801A-Q1

Hello,

I'm facing following questions regarding DRV8801A-Q1 you may help with:

  • How would the lifetime of the driver be affected if it experiences a continuous overcurrent at the H-bridge outputs? I.e. if the driver will keep retrying indefinitely?

  • In case of a short circuit (in the driver IC), is there a risk that the part will catch fire?
    • If yes, how will the driver behave (open-mode or short circuit)?

  • What is the consequence if the supply voltage pin experienced a transient voltage higher than 40V?

Best Regards, Martin

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RE: DRV8801: VPROPI driven low problem

July 18, 2018, 12:14 am
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Could you explain more detail about why during the overcurrent event the current flows the opposite direction?

Is it any relationship with sense trip voltage VTRIP= 0.5V?  when SENSE voltage is above 0.5V, then VPROPI is driven low to 0V. Is it a result or cause?

At this case, which operation mode ( decay) is it for over current? 

Thank you for your time

Best Regards

Gene

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DRV10970: Direction Control

July 18, 2018, 2:04 am
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Part Number: DRV10970

Hi,

Is there a case that the motor rotates in reverse if setting to low or high by using the motor direction control pin FR and changing the phase from 120° to 180° ?

Best regards,
Kato

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RE: DRV8801: VPROPI driven low problem

July 18, 2018, 5:56 am
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Hi Gene,

"Could you explain more detail about why during the overcurrent event the current flows the opposite direction?"

The current through the inductor does not flow in the opposite direction. The current through the resistor flows in the opposite direction.

Please refer to Figure 9 of the datasheet. During normal operation current flows as described by (1), Drive Current. When the voltage across the resistor reaches Vtrip, the outputs are disabled causing the current to flow in the direction shown by (2). The difference is the current flows through the body diodes.

"Is it any relationship with sense trip voltage VTRIP= 0.5V? when SENSE voltage is above 0.5V, then VPROPI is driven low to 0V. Is it a result or cause?"

VPROPI =0 when SENSE voltage is above 0.5V is a result.

"At this case, which operation mode ( decay) is it for over current? "

It is asynchronous fast decay. This means the FETs are disabled and the current flows through the body diodes of the FETs.
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RE: DRV8843: Some questions

July 18, 2018, 6:25 am
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Hi Matsumoto-san,

What is the VM voltage? We will investigate and reply by Friday.

Has the customer considered a different device like the DRV8870? How many different current limit values are needed?
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DRV8843: Some questions

July 17, 2018, 6:03 pm
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Part Number: DRV8843

Hi all

Would you mind if we ask DRV8843?
Please refer to the attachment file, and could you give us the advice?
[View:/cfs-file/__key/communityserver-discussions-components-files/38/20180718_5F00_DRV8843.pdf:1230:0]

Kind regards,

Hirotaka Matsumoto

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DRV595: application related question

July 18, 2018, 6:39 am
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Part Number: DRV595

Hi Team,

My customer has 2 questions:

1.  What if device work at load current >4A?  Since the overcurrent point is 7.5A, so if device output >4A will cause any problem?

2. Since my customer need +/- 5A output current.  Do we have any solution to increase output current?  If  two device can work as parallel?

Thanks.

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RE: DRV8801: VPROPI driven low problem

July 18, 2018, 7:52 am
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Hi Rick,
For the on-board charger application, what is the recommended operation mode when using DRV8801 for locking the charging gun? what is the consideration?
In the low side slow decay mode, does overcurrent still brings the VPROPI to 0?

Much appreciated
Gene
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RE: DRV10970: Direction Control

July 18, 2018, 2:13 pm
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Hey Kato,

I'm sorry, I'm not sure I understand the question. Since I think you're interested in the conditions need to make a motor spin in reverse, I'm going to explain how to do that using the DRV10970. Please correct me if this is not the information you are interested in.

The only condition needed to spin the motor in reverse is to change the logical input of the FR pin. As shown in your picture and below, the FR will change the sequence that the DRV10970 with commutate. The "U phase is leading V phase by 120" phrase is used just to illustrate that the applied phase voltages are 120 degrees out of phase with each other where U will lead the sequence because the waveforms are periodic. The hall sensor configuration does not need to be changed. This behavior works in both the trapezoidal and sinusoidal commutation mode.

Let me know if this doesn't answer your question.

Best,

-Cole

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DRV8873-Q1: Estimated date that this IC will be on the market

July 18, 2018, 4:52 pm
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Part Number: DRV8873-Q1

Hi,

We have requested a full datasheet of this IC and after taking a look at that, we think this could be a good candidate IC for motor control.

So could you please give an estimation of when this IC could be introduced to the market? Is it gonna be in a short or long term?

This information could help us to decide to select this IC or go with an alternative while it is still in preview.

I am really looking forward to your response.

Thank you.

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RE: DRV8843: Some questions

July 18, 2018, 4:58 pm
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Rick san

Thank you for your cooperation!
We are wait for your reply.

What is the VM voltage?
->24V

Has the customer considered a different device like the DRV8870?
->Yes, they has. However DRV8870 is more expensive compared with DRV8843 per CH.

How many different current limit values are needed?
->Aout : Avref=1.8V, Isens=1.2ohm ->0.3A limit
->Bout : Avref=3.3V, Isens=GND -> No limit, only OCP, or maximum setting

Kind regards,

Hirotaka Matsumoto

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