I think you mean 400uA for VREFO?
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RE: DRV8834: VREFO bypass cap
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RE: BOOSTXL-DRV8301: Control Register 1 resets to 0, and motor stops spinning
Sanmesh,
I'm not sure if we have enough data to make that conclusion yet. There are a couple things we would need to check to confirm that the power supply wasn't good enough. Here's a list if you want to check them.
- If board power supply is an issue, then you should see a large dip on the 3.3-V line.
- The timing of this ringing signal is in nanosecond range. I typically don't trust oscilloscope noise/ringing measurements in the nanoseconds range because they are usually due to probe coupling. To properly measure signals in the nanoseconds range, you need as small of a ground loop as possible for the scope probe.
If noise on EN_GATE is truly the issue, the datasheet recommends adding a capacitor. You could put a 0.1 uF or 1 uF cap on EN_GATE. Maybe you can solder it in parallel with R6.
One thing that your oscilloscope picture does tell us, even if the measurement comes from probe coupling, is that something in the system switches at that time. In your experiment, how did you correlate the control register 1 read of 0x00 with this EN_GATE ringing?
If the ringing and the register change have good correlation, here are some other debug items to look at.
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RE: DRV8834: VREFO bypass cap
Hi Marc,
Yes, it is 400uA for VREFO. The 40uA I mentioned is the absolute max current the MCP4726 VREF pin would sink.
In reality, the current should be ~10uA (2V/210kOhms) typical unbuffered, and probably less buffered.
Yes, it is 400uA for VREFO. The 40uA I mentioned is the absolute max current the MCP4726 VREF pin would sink.
In reality, the current should be ~10uA (2V/210kOhms) typical unbuffered, and probably less buffered.
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DRV8834: VREFO bypass cap
Part Number: DRV8834
I see in the DRV8843 data sheet that you should not place a bypass capacitor on this pin. I have inherited a design where this directive was ignored and there is a 0.1uF cap on this pin. I'm getting some units where the DRV8843 is failing, though all the input signals are correct (also, motor voltage supply is 8V max). I'm wondering if a bypass cap on this pin (perhaps over multiple power up/down cycles) could cause damage to the chip leading to inability to step?
Related - the design has VREFO going thru a resistor-divider DAC and back to AVREF/BVREF. My question is, does VREFO modulate at all (i.e. for current limiting, during certain phased, etc.) or is it always a constant 2V nominal?
Thanks,
Marc
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RE: DRV8302: Gate drive troubleshooting
Hi James - here is scope picture - and animations from scope testing of SH_A to 50kOhm to GND from my modified board.
As you might remember I am lineary changing INH_A duty, and this is latest scope traces:
You can see that both gates are open at the same time... How is that possible? That will make short of Phase_A I believe...
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RE: DRV8825: DRV8825 Diver capability
Hi Darren,
With proper heat sinking, the DRV8825 is capable of driving 2A at 36V. The DRV8825EVM is available to evaluate the operation of the device.
If 2A is full scale current, please also consider the DRV8880. This device includes AutoTune.
With proper heat sinking, the DRV8825 is capable of driving 2A at 36V. The DRV8825EVM is available to evaluate the operation of the device.
If 2A is full scale current, please also consider the DRV8880. This device includes AutoTune.
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DRV8825: DRV8825 Diver capability
Part Number: DRV8825
Hi，we want to use DRV8825 to design as motor Driver，the The demand parameters are as follows
1. Bipolar stepper motor drive，Drive 36V/2A motor Step control--- we find the DRV8825 in TI web，houwever，we only find the Driver current is 2.5A while the VM=24V，because our VM=36V，so I need your help to check whether the DRV8825 can Driver current =2A，VM=36V，tks！
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RE: TINA/Spice/DRV8814: TINA-TI Transient Model
Hi Stuart,
We will get back to you on this soon.
Thanks and Regards,
Atul
We will get back to you on this soon.
Thanks and Regards,
Atul
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gate driver mosfet N and P 100% CONTINUOUS
Hello
I need to control a motor from 10% to 100%, a voltage of 12v to 16v, nominal 14v, a maximum continuous current of 15A without motor, with a peak with no start of 60A maximum, with a frequency of 10khz. If I have a duty 10%, and current 15A, and if I use a free-wheel diode circuit, I would have a loss p = vd * (1-duty) * Imax, where vd is the diode drop, vd = 0.6, P = 0.6v * (1-0.1) * 15A, I would have a loss of 8.1W, but I have a size restriction and it would be difficult for me to be able to remove all this heat. Then I thought of a synchronous system with two mosfets, Half-bridge driver encounter to work continuously (100%), so I thought of a P and N mosfet, but I did not find a half-bridge driver, I'm probably looking for the wrong terms.
Summary: Is there any model half-bridge driver for mosfet N and P for frequency of at least 10khz?
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DRV8302: What is the Gate Drive Regulator Power Limit?
Part Number: DRV8302
Power supply is 50V. Power into the DRV8302 PVDD1 and PVDD2 is protected by a ferrite choke and a 55V zener.
I am running 6x 100nC Qg FETs and switching all of them at 30kHz. 100E-9 x 6 x 30E3 = 18mA. Once I get to 25-35% duty cycle and a little over 60A motor current, the DRV8302 GVDD fails and stays <=1.7V until I replace the DRV8302. This is very repeatable. Under no load, I can spin the motor to 100% duty cycle with no problems. Don't know why motor load would affect gate drive power. There could be a clue there.
DRV8302 datasheet page 13 says "The three-phase gate driver can provide up to 30 mA of average gate driver current. This can support switching frequencies up to 200 kHz when the MOSFET Qg = 25 nC"
So either the GVDD <= 1.7V is a symptom of something else broken (everything else seems to be OK) or the regulator is breaking when it shouldn't break. 25nC switching at 200kHz means my 100nC switches should work at 50kHz.
I suspect that 30mA number should be specifying a total power dissipation in the regulator ie 30mA@ 30V PVDD1 means Ptot GVDD = .6W. I'm dropping 40V across GVDD regulator so that would put my limit at 15mA, if my suspicion is correct. Can anyone verify this?
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RE: gate driver mosfet N and P 100% CONTINUOUS
Hi Milordy,
Are you referring to a brushed motor driver or a brushless motor driver?
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RE: gate driver mosfet N and P 100% CONTINUOUS
Hello,
Would be for motor brushed.
Would be for motor brushed.
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RE: DRV8302: What is the Gate Drive Regulator Power Limit?
Hi Nick,
We will investigate and reply by Wednesday.
Are you using trapezoidal or sinusoidal control?
We will investigate and reply by Wednesday.
Are you using trapezoidal or sinusoidal control?
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RE: DRV8302: What is the Gate Drive Regulator Power Limit?
Sinusoidal Control.
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RE: DRV10975: Current limit
Dear Zhao
Sorry for late reply.
1. Yes, the motor is used to drive the wheel through a mechanical differential
2. I am not sure about it. The speed without load is enough, however, it stop when load is applied. I wonder it is the protection of the motor driver or not, but the peak current does not exceed 0.3A, and it return lock current limit detection error.
Pok Man
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RE: DRV8702-Q1: MODE pin / Hi-Z
Hi James, thanks a lot for the answer & confirmation.
Best Regards, Martin
Best Regards, Martin
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DRV8702-Q1: MODE pin / Hi-Z
Part Number: DRV8702-Q1
Dear Team,
our customer would like to use the DRV8702 in PWM mode.
2 Questions:
1) The data sheet states that the pin should be in HI-Z. Do we understand it correctly that this means to keep the pin open / floating?
2) The internal connection of the MODE pin is shown in the data sheet, see below. But isn't there a mistake with the first comparator being compared to 1.35V? With the voltage divider of 26k to 65k, the internal DVDD of 3.3V would give 2.35V. So there would not be a difference between HI-Z or 3.3V @ MODE?
Looking forward to your feedback.
Best Regards
Martin
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RE: gate driver mosfet N and P 100% CONTINUOUS
Hi Milordy,
The majority of high current brushed drivers use N-channel FETs for both the high and low side. This is done by integrating either a charge pump or a bootstrap capacitor.
If you desire 100% operation, the charge pump is the preferred choice. The DRV8701, DRV8702-Q1, DRV8703-Q1 can control a N-channel low side FET and a N-channel high side FET. Please consider these devices.
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RE: TINA/Spice/DRV8814: TINA-TI Transient Model
Hi Stuart,
I think the model library file you are using is encrypted using P-spice model editor, which is why you are getting that error. I will follow up with you by sending an email internally.
Thanks,
Ayon
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RE: TINA/Spice/DRV8814: TINA-TI Transient Model
Yes, I agree with your assessment. I will wait for your follow up.
Thanks,
Stuart
Thanks,
Stuart
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