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RE: DRV8884: RMS current not measured as designed in circuit

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Hi Uhtis,

Can you provide the RREF value, MODE, TRQ and DECAY settings, and a screen shot of the current?

RE: DRV8711 eval: no function at all

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Sorry Thorsten Ostermann

I was intended not to waste the space in TI forum by opening a new thread

DRV8711 eval: no function at all

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I purchased a DRV8711 EVM to so if the DRV8711 is a possible replacement for the A4988. I had some trouble with the first board like the FAULTn LED not being lit as mentioned in another thread. Apart from that, I can not even activate the output stage. I did some measurements and found V5 not beeing present. According to the datasheet this is the 5V output from the DRV8711, so this voltage should be present even when the device is in sleep mode?!

The only function I see is the blinking status LED. I'm also not sure if communication between PC, microcontroller and DRV8711 is working as expected. Is there any way to check that? E.g. a simple SPI read to a certain register? Should the blink frequency of the status LED change during a transfer?

I already returned one board with V5 not beeing present and purchased a new one, but the problems still exist with the new board. J1 was missing on both boards, but adding a jumper to "JTAG" position doesn't make a difference.

Power supply is 24V= from a smal lab supply. Operation system is Win7 (32bit!).

With kind regards,

Thorsten Ostermann

RE: DRV8301: Catastrophic failure, transistors and DRV

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Hi Larry,

I was thinking PVDD, but you have that covered.

Please examine the SH_x pins for negative voltages. Please let me know how low the voltage is with respect to PGND.

A scope shot would be ideal.

DRV8323R: PCB Symbols/CAD drawings?

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Part Number: DRV8323R

Hello -

TI geerally provides bxl files for each component, which can be used to generate PCB footprints and symbols for various software packages.

I do not see one for the DRV8323 (DRV8323RH specifically is what I am looking for). Can someone please advise where I can get this?

Thanks,

-asifjahmed

RE: DRV8301: Catastrophic failure, transistors and DRV

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Hi Rick,

It looks as though the SH_x pins are getting between 10 and 15v below PGND. We didn't run it as hard as the failure points and the transitions seemed to get smaller with high current (although that could simply be due to the commutation point moving slightly). I'll try a Schottky on th e SH_x connections as well as clamping the gates.

DRV10983Q1EVM: Abnormal Back EMF

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Part Number: DRV10983Q1EVM

Hello Sir/Madam, 

I am trying to spin a 6V BLDC with the DRV10983Q1-EVM by connecting the three phases to U,V,W and supplying 7V. I have programmed phase resistance and Kt value by:

1. Measuring no load resistance between two phases and dividing it by 2

2. Kt= [6/(40,000 rpm/60/2 pole pairs)]  ~ 18 mV/Hz . I have tweaked the value of Kt by +- 30% from this value to get it up and spinning. 

However, I see a back EMF error Code 2 as the system moves to closed loop. This however does not stop motor operation as I have disabled lock detect on the software GUI. I would like to understand what am I doing wrong and if this would affect the torque curves and characterization of the motor?

Please see attached image above.

Thanks,

Ganesan M.

RE: DRV8323R: PCB Symbols/CAD drawings?

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Hi Asif,

Thank you for pointing this out. These were missed. We will put in a request for the bxl files immediately.

This may take some time to appear.

What layout package are you using?

RE: DRV8312: researcher

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*********************************************************************************************************************************************************

9.2.1.2.6 Output Inductor Selection

For normal operation, inductance in motor (assume larger than 10 μH) is sufficient to provide low di/dt output (for
example, for EMI) and proper protection during overload condition (CBC current limiting feature). So no
additional output inductors are needed during normal operation.
However during a short condition, the motor (or other load) could be shorted, so the load inductance might not
present in the system anymore; the current in short condition can reach such a high level that may exceed the
abs max current rating due to extremely low impendence in the short circuit path and high di/dt before oc
detection circuit kicks in.

**********************************************************************************************************************************************************

>>However during a short condition, the motor (or other load) could be shorted,

What "other Load" is this referring to?

Also:- Can you provide a mathematical reason as to why an O/P inductor is required? That would be greatly appreciated.

DRV8312: researcher

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Part Number: DRV8312

Pg. 13 of the data sheet states the following:-

" It should be noted that a properly functioning overcurrent detector assumes the presence of a proper inductor or power ferrite bead at the power-stage O/P".

Is this over and above the motor inductance? And if so why?

RE: DRV8860: replace DRV8860

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Hi user503335153,

You did not specify the relay voltage and currents. Assuming the relays are 12V and less than 140mA per relay, the DRV777 may fit your needs.

DRV8860: replace DRV8860

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Part Number: DRV8860

DRV8860  as relay driver  in my  PCB,but it is  too expensive ,can  you  recommend another device instead of it.

RE: BOOSTXL-DRV8323RS: BLDC motor torque control

RE: BOOSTXL-DRV8323RS: BLDC motor torque control

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Hi Rick,

Thanks for the quick answer. If I understand it correctly, in terms of hardware, DRV8323RS also has the current sensor going to MCU ADC, just like DRV8301.

But the MSP430 MCU might not be powerful enough to run the F2802 InstaSPIN code for torque control algorithm. 

Is that correct?

BOOSTXL-DRV8323RS: BLDC motor torque control

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Part Number: BOOSTXL-DRV8323RS

How to use firmware to do torque control run of a BLDC motor with BOOSTXL-DRV8323RS launchpad board?

Didn't find much information after googling. 

Is it a well-known and solved problem? Thanks


RE: DRV8884: RMS current not measured as designed in circuit

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Hi Rick,

Please see thedetails..

RREF = 562K

MODE =1/4 

TRQ = 100%

DECAY = tied to DVDD (slow decay)

DRV10983-Q1: Can't control speed, spin from stop to max then repeat

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Part Number: DRV10983-Q1

So I made my board according to the eval board. Without doing any configuration, my motor spins from stop to max speed and stop for few seconds and repeat. Any idea?

RE: DRV8801: Voltage available for PWM

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Hello Shankar,

The DRV8801 device is able to drive from 8V - 36V, so 16V should be no problem. When you are applying 16V to VBB, what is the VCP voltage?
How are you controlling the motor (enable, mode1, mode2)?
Have you tried not PWMing but applying a constant high signal (100% DC)? what happens then?

RE: DRV8884: RMS current not measured as designed in circuit

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Hi Uhtis,

Based on the value you provided for RREF, the chopping current should be from 50mA to 57mA (this is not considering tolerance from resistor) so 60mA seems correct based on the current regulation equation provided on section 7.3.4 on the datasheet.
For an output current closer to 75mA please use a 400kOhms resistor. Thank you.

RE: DRV8801: Voltage available for PWM

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Hi Luis,
Thanks for the response. Since the pin 13 (Vcp) is not exposed as a pin connection in the Polou board, I haven't tried measuring it. I'm using the DIR and PWM pins to be set high and 255 respectively in my WeMos code which in my understanding is as good as stable DC..however, I'll try your suggestion too and revert shortly.
From what you mention above, this is not normal right? As in I should be able to see all the Vbb being delivered to the Out+ & Out-, right?

regards
Shankar
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