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DRV8320: possible driver leakage pathway that causes phase node voltage rising

April 15, 2019, 3:31 pm
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Part Number:DRV8320

Hi, TI support.

The issue is found while using DRV8320H on my 20V platform 6 months ago. When no FET switching, all three phase node voltages rising up to B+, rising form 0 to B+ takes around 200us. See 2nd picture, 3 phase node all rise to high (after driver power on) at beginning and stay for a long time until software start conducting low side FETs. Then we solved this issue by changing BEMF feedback resistors to 10 times smaller, which is 3.48k and 1k now, see schematic in the 3rd picture.

My teammate found the same issue last week with DRV8350, he has the same power stage design. His BEMF feedback resistors are 110k and 10k at the beginning, phase voltage rise to B+ when supposes to be 0V. After changing to 11k/1k, the phase voltage only rise to around 2V, but motor still not run.

Our questions:

  1.  how can we explain this? is it caused by the leakage curr I draw in the 1st picture?
  2.  Is there a way to avoid this issue, or our schematic can be improved to address this?

Looking forward to your prompt response, we are experiencing a tight schedule.

Thanks,

Yang

   

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DRV8711EVM: The thickness of the copper foil

April 15, 2019, 9:43 pm
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Part Number:DRV8711EVM

Hi all

Would you mind if we ask DRV8711EVM?

<Question1>
How much is the layer of EVM? 2 layer?

<Question2>
How much is the EVM's thickness of the copper foil?

-In case of 2 layer-
 The component side : 35um?
 The solder side : 35um?
-In case of 4 layer-
 The component side : 35um?
 Power side : 70um?
 Ground side : 70um? 
 The solder side : 35um?

Kind regards,

Hirotaka Matsumoto

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The description of nFault in the manual is not intuitive enough. Please help confirm the nFault status as follows

April 15, 2019, 11:19 pm
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The description of nFault in the manual is not intuitive enough.  Please help confirm the nFault status as follows

No over-temperature, over-current, under-voltage, short-circuit and other faults

(After power-on stabilization)

SLEEP

L

L

H

H

EN

L

H

L

H

nFault

　

　

　

　

No over-temperature, over-current, under-voltage, short-circuit and other faults

(instantaneous power on)

SLEEP

L

L

H

H

EN

L

H

L

H

nFault

　

　

　

　

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How to achieve motor phase current inline sensing with detailed waveform variations in hundreds of ns?

April 16, 2019, 12:57 am
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I want to observe the influence of the mos switching on phase current. It happens in hundreds of ns. So the amplifier should have at least a 10ns resolution. Does it indicate the bandwidth of the amplifier should be around 100M? 

The rated phase current is 3.68A and phase resistance is 200mΩ. The voltage across the 5mΩ shunt resistor is around 15 mV, at most 50mV. But the DC voltage is 24V. So the CMRR of the amplifier should be above 10000:1.

At first I want to use a current probe to observe the current directly. I scanned the current probes in tek.com and found that my requirements are satisfied except a new emerged problem. There is input impedance reflected into the phase when using the current probe. And the least value is 36mΩ at 1MHz. I’m not sure if it’s a disturbance comparing the 200mΩ phase resistance since it is not constant, it varies along the frequency and the value can’t be neglected comparing 200mΩ. Is it a disturbance? By the way, the phase to phase inductance is 0.065mH.

Then I turned to differential probe. But the CMRR is 1000:1 at just 1MHz. Obviously, it isn’t enough.

Now I plan to amplify the differential signal first and observe the output of the amplifier. Is there an amplifier meeting all the requirements above? I’ve noticed INA240, but the bandwidth is just 400KHz.

Any other amplifiers or any other solutions?

Best regards.

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DRV8873-Q1: recommended value of bulk bulk capacitor

April 16, 2019, 1:37 am
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Part Number:DRV8873-Q1

Hi,

Data sheet P.46 9.1 'the Bulk Capacitance Sizing' is described that "The data sheet provides a recommended value, but system-level testing is required to determine the appropriate sized bulk capacitor." However, the description of the recommended value can not be found.
Is there a recommended value?

I believe that system testing needs to determine capacitance.
Could you let me know if there is a recommended starting point value?

Best regards,
Yuto Sakai

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DRV8702D-Q1: 24V continuous voltage

April 16, 2019, 3:09 am
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Part Number:DRV8702D-Q1

Hi,

is it possible to run the DRV8702D-Q1 in 24V (max. 36V) continuously?

It is for a 24V battery system, ideally also for 12V downwards compatible.

I in should be at 0 - 10A at -40 to 80 degrees.

Thanks

Fred

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DRV8353RH-EVM: GUI Composer DRV8353Rx v1.0.1 fails to connect to the evaluation board.

April 16, 2019, 4:57 am
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Part Number:DRV8353RH-EVM

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DRV2700: configuration to drive a piezo motor

April 16, 2019, 8:37 am
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Part Number:DRV2700

Hi experts.

I have already asked a question regarding the DRV before. Now I have looked more into the details and have some more questions:

First some information:

- I am using this as the motor: LEGS Linear LS15 from https://piezomotor.com/produkt/ls15/

- I have a DAC to create the control signal for the motor (0 to 5V)

- Desired motor voltage (DRV output) 0 to 45V

- Desired frequency: up to 1.200Hz

- Capacity of the motor is 680nF (not 100% sure about that)

Questions:

1. If I input a sinwave from 0 to 5V, can the DRV amplify that to the same sinwave but from 0 to 45V?

2. Is figure 22 in chapter 9.2.1 in the user manual the corresponding example to my case?

3. Since I only need positive voltage, I connect my piezo element between Out+ and ground. Out- remains unconnected?

4. Since my gain should not change, should I connect the gain inputs to Vcc and GND or to the microcontroller to keep them adjustable?

5. My motor has 4 legs that should work all independently. That means I need 4 DRVs, because Out+ and Out- is coupled?

6. If I connect the DAC to the DRV I only need to connect IN+, right? IN- remains unconnected?

Sorry for all that questions. It would be a huge support, if you could help me out.

Thanks

Sebastian

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DRV8323: PGND and AGND question on datasheet

April 16, 2019, 8:37 am
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Part Number:DRV8323

TI DRV83323 data sheet (SLVSDJ3A), pages 60 & 66, the application notes show the PGND and AGND with the same ground symbol and then a second symbol that has not been defined!  Would you please clarify?

I would like a recommendation relating to grounding of the analog and the power components used in conjunction with the DRV8323S driver(I have concerns on noise from ground bus).  From a technical aspect, how are the grounds different within the driver?

Background:

Using DRV8323S driver to drive a 14A BLDC motor at 18V nominal.  Feedback is supplied by the motor Hall sensors.  The motor is changing directions often.  

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DRV10983: General questions in controlling a motor

April 16, 2019, 1:23 pm
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Part Number:DRV10983

In my previous question, I asked

6. can i hold the motor without moving perhaps by energizing just one phase - typically (100 ms or so)

The response was:

6) With the DRV10983, holding the motor to a specific position is done in the "Align" phase, and you can set the time that this align is done. See section 8.4.3.5.1 Align .

I am not sure how to do this...this is a register in the EEPROM and is one of the setup registers. In order to hold the motor, would I just write bits [2:0] of SysOpt4 to 101 (160 ms)  while keeping bits 7:3 as is?  My general motor scheme is move the motor, stop the motor, hold the motor, repeat.  So can I set the align bits while the motor is stopped, then continue on with moving the motor? Would I have to wait 160 ms after issuing the align command before moving the motor again? 

Thanks

Ken

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DRV110: 2s spike time reasonable?

April 16, 2019, 2:58 pm
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Part Number:DRV110

The manufacturer of my solenoid valve tells me I need to flow maximum current for 2 seconds before I can be sure the valve is closed.  I can back off my current drive to about half of the maximum after 2s.  Is there a problem with using a 22uF Ckeep to get this 2s spike time?  How large can I make Ckeep?

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Sinusoidal control solution

April 16, 2019, 7:24 pm
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Dear support team

My cosutomer considers sinusoidal contorol.

They evaluating BD63030 now, I could not find replacement of TI.

Is there any TI solution ?

■Requirement

・Peak current 10A

・Sinusoidal control

・Sensored control

・Automotive grade

BD63030

www.rohm.com/.../bd63030evk-c-e

Regards

Tomohiro Nagasawa

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Accelerated life test calculator

April 17, 2019, 12:45 am
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Hi,

          I need to conduct Accelerated life test (ALT) for VFD and need to calculate the life span for the product. for the first time I have to calculate the life time of the product and I am not familiar about ALT.

I request you , please suggest me how to conduct the ALT & resolve this issue. If you have any reference ALT test plan calculators Please share me. 

Thanks & regards,

M.yasoda.

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CCS/BOOSTXL-DRV8305EVM: how to replace high side resistors with lower values ?

April 17, 2019, 6:09 am
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Part Number:BOOSTXL-DRV8305EVM

Tool/software: Code Composer Studio

I've been reading the BOOSTXL-DRV8305EVM user's guide. and i saw this paragraph saying that i can change the resistors R8 R9 R10 and R14 with other ones. but I can't see where to change it ? is it through software ?

hope someone can help.

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DRV8824: CP1、CP2 about 1V of overshoot

April 17, 2019, 7:21 am
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Part Number:DRV8824

Dear all：

       I used an oscilloscope to test CP1 and CP2 pins of DRV8824, and found that there was overshoot of about 1V, and the normal amplitude was 11.6v, and the test waveform was as follows：

Consult next what method whether eliminate to cross impulse value?

Thank you！

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DRV10866EVM: Start-up sequence intermittent

April 17, 2019, 7:22 am
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Part Number:DRV10866EVM

Hi,

I am using the DRV10866EVM as a debug setup for my motor control. I am having start-up issues with one of two motors. The first motor has a phase-phase resistance of about 6.3 ohms and no center-tap. I am using a wye connection on the motor leads using 1.6k each to form a pseudo center-tap. When I used 3.2k the start-up wasn't as reliable.

Now for the problem motor. I am using the same driver setup with the same wye connection using 1.6k ohms. The phase-phase resistance was only 2.4 Ohm so I added 2 ohms to each motor lead to get 6.4 ohms phase to phase. The start-up is very erratic. It 'jogs' around in a full revolution and does this about 3 times before it "takes off" and starts spinning normally. The problem motor has an inertia about 1.5x the first motor.

The trace below catches a good startup on the problem motor. I'm triggering on Fg (Yellow). The center-tap is Purple 2v/div. The blue is one of the phase winding's. The time is 4ms/div.

The high frequency on the winding's is about a 6us period, which I assume is the DRV10866 processor (?). The PWM, not shown, is 25 kHz, 50% duty cycle.

*** Any suggestions to get reliable spin-up on first try?

*** Do I need AC filtering on the pseudo center-tap?

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DRV2700: About boost converter.

April 17, 2019, 7:29 pm
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Part Number:DRV2700

Hi team.

I'd like to drive a piezo element at 200V~250V.

I will use a flyback configuration, but I can't see current limit at boost converter.

How many drive current is the DRV2700?

And,  does this device have over current protection?

In the block diagram, I think the current is detected.

Our piezo element will flow about 30=50mA at 200V~250V.

Sincerely.

Kengo.

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About DRV91680 ESD

April 17, 2019, 8:19 pm
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 1.   We use DRV91680 ,  products are as follows, 

2.  DRV91680 will reset  during  ESD 2KV test,  DRV91680 VCC  is  20V normal,  DRV91680 VCC  is about -20V  during  ESD 2KV test.

3.  what should we do to DRv91680 not reset  during  ESD 2KV test.


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DRV8829: About recommended connection method of schottky-diode.

April 17, 2019, 10:13 pm
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Part Number:DRV8829

Hi team.

I'd like to use a schottky-diode.

Do you have your recommendation about connection method of schottky-diode?

I will use all decay mode.

Sincerely.

Kengo.

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DRV10974: Whether DRV10974 can drive brushless motors for aerial models

April 17, 2019, 11:08 pm
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Part Number:DRV10974

Hi Team,

Does the brushless motor used for the aerial models meet the motor parameters as required by drv10974? Like motor A2212, 1400kv.

Thanks.

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