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RE: DRV8832: Need to detect stall condition
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RE: Stepper Motor Driver DRV8835 Voltage Problem
Hi John,
Think of PHASE as current direction. Enable is output on/off. It is the simpler of the two interfaces, although it does not have coast mode (both outputs disabled).
To drive the motor with PHASE/ENABLE, first set the two ENABLE pins high:
For forward direction, begin at step 1 and increase to step 2. After step 4, repeat steps 1 through 4.
For reverse direction, reverse the order. begin at step 1 then decrease by going to step 4, 3, 2, 1.
STEP PHASEA PHASEB
1 0 0
2 1 0
3 1 1
4 0 1
Each step above will move the motor one full step.
Think of PHASE as current direction. Enable is output on/off. It is the simpler of the two interfaces, although it does not have coast mode (both outputs disabled).
To drive the motor with PHASE/ENABLE, first set the two ENABLE pins high:
For forward direction, begin at step 1 and increase to step 2. After step 4, repeat steps 1 through 4.
For reverse direction, reverse the order. begin at step 1 then decrease by going to step 4, 3, 2, 1.
STEP PHASEA PHASEB
1 0 0
2 1 0
3 1 1
4 0 1
Each step above will move the motor one full step.
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DRV11873: Cut-out at certain duty cycles - why?
Part Number: DRV11873
Greetings. I am using a DRV11873 in a custom design. It is driving a small Maxon motor (EC20 flat) at 12V. It generally works as expected, but at certain duty cycles, the driver will cut out, remain off for a few seconds, restart and continue this oscillation until the duty cycle is changed. For example, in my current design, if the duty cycle is set to 81%, the driver works without issue. If set to 82 or 83%, the driver cuts out/oscillates. In these conditions, the motor current draw in in the sub 600mA range. RPM is around 6500-7000 - the FS pin is pulled high. Any ideas regarding what might be causing this? Certainly it should not be an overcurrent or thermal issue. I need to investigate if the motor lock pin is toggling, but certainly the rotor itself is not physically being stopped when these oscillations are occurring
Note that the PWM frequency is set to be 25kHz, which is within the 7-100kHz spec per the datasheet.
Also note that I've experienced this oscillation in the past when using the drv11873 dev board as well.
If I change the loading on the motor when the oscillations are occurring, I can get them to stop. Any ideas about what might be happening? Anything I should be investigating to attempt resolve? This is a somewhat high priority issue since we are moving in to production with this design - rapid feedback appreciated.
-Chris
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RE: DRV8848: Drv8848 controlled by cc3200mod- is not working
Thank you!
I worked, do I need to do the same with Bint?
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RE: DRV8832: Need to detect stall condition
Sundar,
DRV8872 is our catalog device, and DRV8872-Q1 is qualified for automotive applications. Their function and parameters are identical.
The OCP on the DRV8873C is fixed at 1.2 A, as you saw. I spoke to a colleague today about OCP, and I want to correct my statement about using OCP for stall in the previous post. The main purpose of OCP is to protect the IC when the outputs accidentally short to VM or GND. It should not be used to detect stall conditions. There are a few reasons for this: 1) due to part-to-part variation of motors and ICs, a particular OCP setting may not “detect” the stall condition for some systems, and 2) The motor currents at startup come close to the stall currents, so the motor may not start spinning correctly.
If you want to detect a particular current in the motor using the DRV8837C, you could potentially add a resistor in series with the motor, and add a comparator or current-sense circuitry to measure the current in that resistor.
The DRV8850 is the best choice if you want to sense current.
The DRV8848, DRV8833, and DRV8833C offer current regulation. These devices will limit the current during start up and stall conditions. Also you can use the stall-detection method described in the application note in the previous post with these devices.
The DRV8837C cannot implement the stall-detection app note because it does not regulate the motor current with chopping.
The 25 us tOFF time refers to the off time when the current is being regulated. The current regulation method in the DRV8872, DRV8833, and DRV8848 is implemented with “current chopping.” This is similar to PWM, but the off-time (tOFF) is a fixed value for the DRV8872. The datasheet explains current chopping in detail.
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RE: DRV8848: Drv8848 controlled by cc3200mod- is not working
Hi idan,
No, you do not need to do the same thing with BIN1 and BIN2. AIN1 and AIN2 are used to set the device in parallel mode. BIN1 and BIN2 are not used for this purpose.
No, you do not need to do the same thing with BIN1 and BIN2. AIN1 and AIN2 are used to set the device in parallel mode. BIN1 and BIN2 are not used for this purpose.
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DRV8848: Drv8848 controlled by cc3200mod- is not working
Part Number: DRV8848
Hello,
I am using drv8848, controlled by cc3200mod, the driver is connected as shown in the schematics below,
the voltage is 12v, i don't
use pwm, every input is connected to a different port on the cc3200mod, the controller signal are working fine,
here is the problem - when I send a signal to BINT 2 al the Bout and Aout are the same, Instead of only output Bout
Has anyone had this problem and know how to solve it?
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RE: DRV8412: The output is absent
Hi Serafino,
What is the PWM frequency and duty cycle?
What is your bulk capacitor value on the +12V signal? I see each output with a 47uF capacitor to ground but do not see much bulk capacitance.
Can you add a 1k/1k resistor divider from PVDD to GND with the center connection at OUTA? This can help determine if the outputs are really driving to 0, or disabled?
Can you provide a scope capture of PWM_A and OUTA?
If the outputs are disabled, please remove the 47uF and 470nF capacitors on OUT_X1+ and OUT_X1- and try again.
What is the PWM frequency and duty cycle?
What is your bulk capacitor value on the +12V signal? I see each output with a 47uF capacitor to ground but do not see much bulk capacitance.
Can you add a 1k/1k resistor divider from PVDD to GND with the center connection at OUTA? This can help determine if the outputs are really driving to 0, or disabled?
Can you provide a scope capture of PWM_A and OUTA?
If the outputs are disabled, please remove the 47uF and 470nF capacitors on OUT_X1+ and OUT_X1- and try again.
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RE: DRV8840: PWM input to output timing
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RE: DRV11873: Cut-out at certain duty cycles - why?
Chris,
Can you check the FG frequency? It's possible you're hitting a false lock as described in: http://www.ti.com/lit/an/slva778/slva778.pdf
Thanks,
Brian
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RE: DRV11873: Cut-out at certain duty cycles - why?
Brian- Excellent, thank you, this seems promising. I'll measure and report back.
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RE: DRV8332: need help estimating power usage
Hi Rick,
You're advice was helpful as we are now seeing numbers that make more sense. Am I correct in seeing that the body diodes dissipate much more power than the FETs due to the Rds_on resistance?
If the motor is pulling an average 3A I get a much larger number for the body diodes than the Rds_on.
I am curious, why do the body diodes conduct so much? From the data sheet it looks like the diodes should be shorted out by the FET conducting when the FET is on. What is the circumstance that causes the body doides to conduct?
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RE: DRV8332: need help estimating power usage
Hi Rob,
The power through the diode is considerably higher than through the FETs. At 3A, the FET power is ~.72W (I2R) while the body diode power is 3W (VI).
The diodes should only conduct when the FETs are off. This is typically during dead time, but can be extended by the cycle by cycle current limit. If you monitor the voltages and see the voltage switch high or low prior to the end of the PWM cycle, you are probably entering cycle by cycle current limit.
If the cycle by cycle current limit is activated, the remainder of the cycle will use the body diodes. Ideally this can be avoided by monitoring the current and switching to fast or slow decay prior to reaching the cycle by cycle cutoff. The current in fast decay (also referred to as coast) flows through the opposite high side and low side FET. The current in slow decay (also referred to as brake) recirculates the current in the low side FETs.
The power through the diode is considerably higher than through the FETs. At 3A, the FET power is ~.72W (I2R) while the body diode power is 3W (VI).
The diodes should only conduct when the FETs are off. This is typically during dead time, but can be extended by the cycle by cycle current limit. If you monitor the voltages and see the voltage switch high or low prior to the end of the PWM cycle, you are probably entering cycle by cycle current limit.
If the cycle by cycle current limit is activated, the remainder of the cycle will use the body diodes. Ideally this can be avoided by monitoring the current and switching to fast or slow decay prior to reaching the cycle by cycle cutoff. The current in fast decay (also referred to as coast) flows through the opposite high side and low side FET. The current in slow decay (also referred to as brake) recirculates the current in the low side FETs.
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RE: Motor driver IC with open circuit / short circuit detection
Hi Eduard,
As you found, there is a path that consumes current in method 2. Using the 100k resistor limits the current to ~15uA. If you want to raise the voltage at "MECH Override INT" node, you can decrease the resistor to 10k. The down side of this is the current draw will increase to approximately 80uA.
From the circuit provided are you polling the "MECH Override INT" node at a low frequency? If you are, please consider modifying the circuit to insert a second NMOS transistor between the "MECH Override INT" node and the schottky diode. The drain would be connected to "MECH Override INT", the gate connected to "MECH Over Sense ON", and the source connected to anode of the schottky.
By doing this, you can reduce the average current by the operating duty cycle. For example if you measure the current for 1ms every second and the current is 80uA, the average current would be reduced to approximately 80nA assuming there is very little leakage in this configuration. TI femtoFETs ( www.ti.com/.../femtofet.html ) are ideal for these applications due to the size.
As you found, there is a path that consumes current in method 2. Using the 100k resistor limits the current to ~15uA. If you want to raise the voltage at "MECH Override INT" node, you can decrease the resistor to 10k. The down side of this is the current draw will increase to approximately 80uA.
From the circuit provided are you polling the "MECH Override INT" node at a low frequency? If you are, please consider modifying the circuit to insert a second NMOS transistor between the "MECH Override INT" node and the schottky diode. The drain would be connected to "MECH Override INT", the gate connected to "MECH Over Sense ON", and the source connected to anode of the schottky.
By doing this, you can reduce the average current by the operating duty cycle. For example if you measure the current for 1ms every second and the current is 80uA, the average current would be reduced to approximately 80nA assuming there is very little leakage in this configuration. TI femtoFETs ( www.ti.com/.../femtofet.html ) are ideal for these applications due to the size.
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DRV8711: Predriver Fault(XPDF) condtion
Part Number: DRV8711
Hi all
Would you mind if we ask DRV8711?
We would like to confirm Predriver Fault(XPDF) Indexer mode and PWM mode.
<PWM mode>
In PWM mode, if excessive current is detected on the gate drive outputs (which would be indicative of a failed/shorted output FET or PCB fault),
->Acoording to short between XOUT1(or XOUT2) and GND, we guess that it is possible to confirm.
<Indexer mode>
The datasheet shows "When in indexer mode, both H-bridges are disabled, the xPDF bit in the STATUS register is set, and the FAULTn pin is driven low."
As the condition of occurence, is it the same as PWM mode? short between XOUT1(or XOUT2) and GND??
Kind regards,
Hirotaka Matsumoto
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DRV8833: Regenerative braking
Part Number: DRV8833
Hi there,
I'm building a motor driver circuit capable of regenerative braking. Is it possible to achieve this with the DRV8833 chip (i.e. current flow from AOUT1 to VM), or does the chip only allow current to flow from VM to the output?
Thank you,
Ben Hudson
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DRV8841: Possible to control speed of DC through current regulation feature?
Part Number: DRV8841
I'm curious as to whether the current regulation feature of this motor can be used as a very rough speed control for DC motor. Since only 4 levels can be controlled, I realize that it will never have the resolution of PWM control, but my application requires very rough control of 12 separate motors. Is this configuration possible with 12 DRV8841 controllers?
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DRV8701: 36V 300A motor controller design
Part Number: DRV8701
Hi -
I would like to use DRV8701E to drive a brushed DC operating at 36V at up to 300A max for at least 60sec. Continuous max current is about 140A. This is to drive a bidirectional motor.
The data sheet refers this part is targeted to 12-24V bidirectional motor. Any issues with using this part for my application?
Thank you,
Daniel
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DRV10983: USB2ANY purchasing
Part Number: DRV10983
Hello team,
My customer is using DRV10983 for their application.
For production, they need USB2ANY.
Can customer purchase only USB2ANY?
Could you help for this requirement?
Thanks.
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RE: DRV8412: The output is absent
Hi Rick, the frequency is 7.37kHz and the duty cycle is 50%.
The bulk capacitor on +12Vdc is 100uF
With and without the partitor the situation is the same. But if I remove the capacitor after the inductors, I can see the waveform.
I would say that I'm using this capacitor value since I see this in the development board of the DRV8412.
So my question is: should I use some capacitor at the output or not?
The use of series inductor is necessary or also this could be removed?
Thank you for your support
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