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RE: DRV8800: DRV8800 Abnormal output, can not be used normally

January 5, 2018, 6:13 am
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Hi Ming,

How many products are showing abnormal operation? How many are operating properly?

Can you provide any scope captures of the current or voltage at the outputs and at VCP?
Ideally, please provide the scope captures zoomed out and zoomed in showing good versus bad behavior.
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DRV8800: DRV8800 Abnormal output, can not be used normally

January 4, 2018, 11:06 pm
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Part Number: DRV8800

hi all 

During the use of DRV8800, some products were wrong. Under normal circumstances, the voltage between OUT+ and OUT- is 11.3V, and the device supplies 12V. When abnormal, the voltage between OUT+ and OUT- is 9.8V or no voltage or other numbers.
Do not know what cause?
What aspects need to be improved?

The following are the schematic ：

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RE: DRV8884: Motor Current not stable

January 5, 2018, 7:12 am
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Hi uhtis,

Can you confirm the TRQ pin is set to 1? If TRQ=1, the current should be set to 26.5mA.

When operating at 53mA, this is similar to operating at the 5% current at 1A. Please note the current trip accuracy (IRREF = 1.0A, 10% to 20% current setting). At such a low level of current is +/- 25%.

There are a couple of options to try, assuming the TRQ pin is set to 0 instead of 1.

1) Change the RREF resistor to 281k and the TORQUE setting to 1. This will reduce the blanking time to 1us and may help.
2) Consider a different device like the DRV8880 with external sense resistors to boost the voltage to the comparator. The DRV8880 with a 2.37V VREF, 6.8 Ohm sense resistors, and a TRQ setting of 11 will increase the voltage to the comparator.
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RE: MSP-EXP430G2: Cannot read the data of DRV8711 on BOOST-DRV8711

January 5, 2018, 7:27 am
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Hi Kaka,

Are the jumpers configured per section 3.2.1 of the user guide? Please note jumper P1.6 can affect operation of SDO.
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MSP-EXP430G2: Cannot read the data of DRV8711 on BOOST-DRV8711

December 20, 2017, 12:35 am
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Part Number: MSP-EXP430G2

Hi TI Experts,

We met the following issue now.
When I evaluated the BOOST-DRV8711 with MSP-EXP430G2 and default source code and GUI which TI provided on Web site, the GUI could not read the read the data of DRV8711. Then I checked the waveform of SPI data line, the MISO(SDATAO) data line was about 2.0V even thought other line was 3.3V. Please check the attached the waveform.

CH1: CLK(SCLK)
CH2: MISO(SDATAO)
CH3: MOSI(SDATI)
CH4: SCS

Would you please teach me the reason why this phenomenon was occurred?
Best regards.
Kaka

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RE: BOOST-DRV8711: what is the response time of DRV8711 to reach position ?

January 5, 2018, 10:39 am
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BOOST-DRV8711: what is the response time of DRV8711 to reach position ?

January 3, 2018, 4:15 am
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Part Number: BOOST-DRV8711

Hi, How long time the DRV8711 took to execute step move?

Lets take an example,

Configuration: 16 - usteps, speed - 240 RPM with no_load, step_index input - 4. How long should wait to read encoder feedback after given the step index pulse?

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RE: BOOSTXL-DRV8305EVM: Call FAST estimator firmware in TMS320F28027F's ROM with MATLAB / Simulink

January 5, 2018, 11:39 am
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The only way you would be able to do this would be to use an InstaSPIN-enabled C2000 device as processor-in-the-loop, calling EST_run() from the device itself. We do not provide any FAST library for Matlab/Simulink usage

Sean
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BOOSTXL-DRV8305EVM: Call FAST estimator firmware in TMS320F28027F's ROM with MATLAB / Simulink

October 16, 2017, 2:32 am
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Part Number: BOOSTXL-DRV8305EVM

Hi,

Our project needs to be done in MATLAB / Simulink, so we won’t write code in CCS directly.

We want to use only the FAST estimator firmware like this:

How can we integrate Motorware in MATLAB / Simulink?

Best Regards

Marcus Richters

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RE: DRV8823: Unable to control the motor using DRV8823 module

January 5, 2018, 12:32 pm
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Hi Swapnil,

If the transaction was successful, the outputs should be xOUT1=H and xOUT2=L.

You should be able to measure this with a DMM and with the motor disconnected.

The clock does not look very clean in the image. Is it possible noise is causing the SCLK to be seen as too many clocks?
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RE: DRV8823: Unable to control the motor using DRV8823 module

January 5, 2018, 12:51 pm
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Thanks for the reply.

I think it looked noisy in that picture because of the scale. When I zoom in, it is pretty clean (as well as all the other signals).
Could it be over current issue? but my Out pins are just floating.

Swapnil
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RE: DRV11873: Lock Detection functionality

January 5, 2018, 1:18 pm
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Na Na,

Sorry for the delay. Message got lost in holiday activities.

1. For the false lock to occur the FG frequency must be close to the internal clock frequency. It's the internal clock frequency that can vary by +/-30%. So it is possible that the motor will function without false detect inside the +/-30% range of the clock frequency just poses a risk that you might see false lock detect.

2. Yes, any multiple of the clock frequency can cause the false lock detect. Since 1kHz is near the center of the clock frequency it is quite likely that you are hitting the false lock detection described in SLVA778.

Thanks,

Brian

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DRV11873: Lock Detection functionality

December 21, 2017, 12:36 am
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Part Number: DRV11873

Hi

According to SLVA778, FG frequency at multiples of internal sampling clock can result in false lock conditions.

1.

Does it mean if FG matches N x 101.6Hz, lock detection would be happened?

2.

Is False Lock Detection likely to occur all the DRV11873 under certain conditions?

BestRegards

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RE: DRV8823: Unable to control the motor using DRV8823 module

January 5, 2018, 1:20 pm
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Hi Swapnil,

Overcurrent is unlikely unless you have a component connected to the outputs that would draw >1.5A for >2.5us. Large capacitors, zeners or TVS with incorrect voltage ratings, or diodes connected in the wrong direction could cause this.

Assuming you wrote 0xFFF0 first, please place the scope on you should see an AOUT1 or BOUT1 go high for a few microseconds. This will indicate the transaction was accepted, and then the device entered a fault condition which requires a power cycle.

If you wrote 0xFFF8 first, COUT1 and DOUT1 should be observed.
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DRV8823: Unable to control the motor using DRV8823 module

January 5, 2018, 12:04 pm
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Part Number: DRV8823

Hi,

I am trying to control a DC motor using DRV8823 module but I cant it working. 

VM = 12.0 V

Rsense = 0.66Ω, Vref 3.33V ( I shorted V3P3 with ABVREF and CDVREF) 

I used same capacitors as the one from typical application diagram. I have also shorted SLEEPn pin to V3P3 pin, so that it is always high. RESETn pin is controlled by GPIO from the TMS320f28335 (It is always high).

I am keeping SSTB pin as high all the time. I am sending 0xFFF0 and 0xFFF8 over the SPI as mentioned by  in this thread. 

This is my probed SPI message. 

1 - Yellow = SSTB

2 - Blue = SCS

3 - Magenta = SDATA

4 - Green = SCLK 

I probed VCP relative to VM and I am seeing 10 V. 

Should I be seeing any voltage between AOUT1 and AOUT2 or any other motors? 

Thanks 

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DRV8332: need help estimating power usage

January 5, 2018, 2:08 pm
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Part Number: DRV8332

Hello,

We are using the DRV8332 motor driver in a design that is getting ready to go into small quantity production.  We need to do a thermal analysis on the design and therefore I need to figure out how much power this chip uses under load. 

I'm assuming the 3 phase BLDC motor draws 3A at 24V when being driven under full load.  I need some guidance as to calculating the power dissipated in the DRV8332.  

My initial idea was to use I^2 * R where R is the Rds_on of the FETs in the driver.  I got 80 milli ohms from the data sheet which specifies a single FET so I doubled that to 0.160 Ohms.  So, my initial power estimate is 9A*0.160 = 1.44W.  This estimate alone doesn't seem to match with our bench testing when analyzing how hot the chip gets and when it over heats and shuts off.

Does anyone have any guidance as to how I could more accurately calculate a power estimate in this situation?  Does the PWM waveform/gate driver switching play a role?  What other things should I take into account and how would I go about doing that?

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RE: DRV8823: Unable to control the motor using DRV8823 module

January 5, 2018, 2:10 pm
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Hi,
Thanks for your help. I got it working

My data signal was being sent at the exact same time as the rising edge of the clock.
I added the phase delay for the clock and it fixed the problem.

Thanks!
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RE: DRV8332: need help estimating power usage

January 5, 2018, 3:24 pm
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Hi Robbie,

Have you measured the current in the motor to determine you have 3A?
How far off do you think you are?

There are a few items that can help improve the calculation or improve the performance:
1) Please note Figure 3 of the datasheet, which will help you estimate the RDS(on) as the junction temperature increases.
2) How long will the body diodes conduct current? This can be several W (Vf * I).
3) How long is the high side on without refreshing the boot capacitor? This can lower the Vgs, increasing the RDS(on).
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RE: DRV595: Differential Input

January 5, 2018, 4:06 pm
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Hi Shawn, thanks for the response (I'm working with Sukwon). I'm still puzzled, though, as the data sheet says the common mode input range is from 0.5 to 4.5V, and there are several plots showing behavior over that range and more. I understand that the amplifier inputs may be biased at 3V, so if we're at nominally 1.25V then we'd have an input bias current of 30uA to deal with (60kOhms at our gain of 20dB), but we're OK with that. Is there some reason the '595 can not be operated with a wider common mode input? Thanks.
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DRV595: Differential Input

January 3, 2018, 11:18 am
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Part Number: DRV595

Hello-

I am using DRV595 to drive TEC. In the datasheet, it says "To use the DRV595 with a single-ended source, use a voltage divider to bias IN- to 3.0V, and apply the single-ended signal to IN+." Is there a reason why it needs to be specifically biased at 3V? Will it be okay to bias IN- to 1.25V and apply the single-ended signal to IN+?

Thanks,

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