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DRV8304: Dead time adjustment questions

March 25, 2019, 9:16 am
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Part Number:DRV8304

I’m looking at DV8304H and calculating losses for different MOSFET power stages.

The datasheet states that the dead time is not a fixed value, but has a typical value of 120ns for the HW version of the DRV8304.

Is it correctly understood that DRV8304 adjusts the dead time automatically, dependent on the switching time of the MOSFET? If so, why is it possible to adjust the dead time on the SPI device?

 I’m looking at MOSFETs that have 30ns-60ns in switch on time and 10ns to 30ns in switch off time - My concern is that if the typical dead time is 120ns, it will result in significant power losses due to the freewheeling diode.

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DRV8302: Motor Stuttering issue at slow speeds

March 25, 2019, 9:36 am
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Part Number:DRV8302

Hi,

My customer wants to implement a Sensorless BLDC motor controller.

Conditions and parameters:

Min speed of 300 RPM

Start time 150ms

4Pole Motor with downstream gear box (32:1)

DRV8301/DRV8302 EVM is used with ISO-Control Card

TI Motorware SW

Issue:

Motor doesnt start/run smoothly. especially at slow speeds in the range or 300 RPM

After 500RPM, the motor runs fine.

Thanks,

Needhu

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DRV8305: nFAULT asserted with no faults or warning in registers, increased current draw

March 25, 2019, 9:50 am
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Part Number:DRV8305

This is my first time using the DRV8305 and so far it's been a great part to work with. During development I found that two parts had failed. The parts showed increased current draw and stopped responding to inputs. At the time I wasn't able to thoroughly investigate the failures as I should have. Then for a long time I saw no failures but a couple just popped up again. This time I was able to investigate the failures further and found the following.

The failure presents as before, the parts have an increased current draw and the nFAULT line is asserted. The increased current draw suggests that there is physical hardware damage. As expected, the high-side gate driver charge pump is not running and PWM inputs to the chip are ignored. When reading the warning and fault registers (addresses 0x1, 0x2, 0x3, 0x4) all reads return 0. Reading out the rest of the configuration registers reflects the configuration with which the part is initialized, which are default values for the most part. Reading the warning and fault registers does not clear the fault condition, neither does toggling the EN_GATE line, the warning and fault registers read 0 as before.

As I was unable to find any hints to what might have caused the fault and potential damage to the IC I started reviewing the datasheet to see if I made a mistake in the design that could have caused the problem. So far the only thing I've found is that the datasheet mentions that DVDD and AVDD should be bypassed with a 1uF capacitor, I've got that. Additionally it mentions that DVDD and AVDD should _not_ be supplied externally. It appears that I had missed this note (pg. 25, section 7.3.6) and added a zero-ohm resistor to power DVDD and AVDD from 3.3V and 5.0V, respectively. So far this is the only mistake I've found.

Could having supplied DVDD and AVDD externally (with 3.3V and 5V, respective) have cause such a failure? I understand that it might be difficult to answer with any reasonable amount of certainty, I was just wondering if anyone had any insight. Currently my best option is to remove the 0-ohm resistors which allow for DVDD and AVDD to be supplied externally and run some long term tests and see if the parts survive. This is a difficult way to prove (or even suggest) that the root cause has been found and solved but it's the best I've got at the moment.

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DRV8353: How much is Vvcp at 48V of Vvm?

March 25, 2019, 7:08 pm
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Hi team.

I'd like to know about Vvcp.

How much is max and min voltage of Vvcp , when Vvm is 48V ?

I can not determine the correct value of Vvcp, because I can't see the correct values from below the graph.

]

Sincerely.

Kengo.

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DRV10987: About linear mode

March 25, 2019, 10:21 pm
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Part Number:DRV10987

Hello support team,

(1) The current range is 5 mA in linear mode using step-down regulator with resister.
I think this current is amount of I(VREG), I(V3P3) and I(V1P8).
In other words, I think that it is recommended to use the total of these currents at 5 mA or less.
Is my understanding correct?

(2) Does the 5 mA of current in above (1) include the internal current of the IC?

(3) Specification of the EEPROM retention is 10 years at minimum. but how good is it?
How long is the actual capability of retention?
Of course I understand that there is no warranty for more than 10 years.

Sincerely,
M. Tachibana

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DRV8432: DRV8432 burn GND-C/D and OUT-D when 24V power up

March 26, 2019, 12:20 am
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Part Number:DRV8432

hi ,

Recently we have a product that use DRV8432. But there are 4 pieces out of 200 had burn the OUT-D and GND-C/D, OUT-B and GND-A/B when 24V powered up.  Can anybody tell what is the potential reason? thanks a lot.

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DRV8308: Review the schematic

March 26, 2019, 3:30 am
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Part Number:DRV8308

Hello,

Can you help to review the schematic as attachment?(Please visit the site to view this file)

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DRV8838: Current Leakage onto the output

March 26, 2019, 3:49 am
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Part Number:DRV8838

Hi there everyone,

I am driving a tiny coil with a constant current source. In order to be able to reverse the current flow direction at the coil, I've connected the coil to a DRV8838 H-Bridge, which in turn is driven by that constant current source. The issue that I am having is that the measured current at the coil does not match that of the DRV8838 input.

I have taken samples of both parameters in the range of operation that I am running the device at, in both reverse and forward, and the results both show the same trend:

  • Both graphs show an initial current of 0.27 - 0.37 mA, suggesting that there is leak from somewhere else, since the current source is sourcing 0 mA.
  • The slope of both graphs is less than 1, so they both eventually reach a point where I_coil = I_source, this roughly happens at around 6.5 - 7 mA in both cases.
  • Past the 6.5 - 7 mA point, the current measured at the coil starts to be lower than that supplied by the current source. Suggesting that now the current from the current source appears to be sinking somewhere else other than on the coil.

I would really appreciate any insight into why this is happening. At first I suspected it might have something to do with the H-bridge gates leaking current onto the coil circuit, but the situation reversal after 7 mA has got me thinking it might be something else.

Thanks in advance,

Dani

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DRV8320: SDO timings

March 26, 2019, 4:36 am
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Part Number:DRV8320

Hello,

We have a question regarding the SDO output characteristics of the DRV8320.

The datasheet is stating Td(SDO) SDO output delay time at 30ns.
Is that pure internal delay ie. time to drive the gate of the open drain internal mosfet or does it take into account the rise time outside of the component ?

We are asking this question as the datasheet does not provide the test conditions that led to the timing stated in the datasheet.

To ensure our design works, which was not the case at the beginning due to link frequency vs rise time, we did some tests with different pull-up values as highlighted in the below screenshots (don't pay attention to the labels, the yellow one is the clock and the purple one the sdo). 

With a 4.99k:

With a 1k:

If the datasheet doesn't take into accout the rise time, it misses an information on the output capacitance of the DRV8320 which would allow us to compute it.

From our tests, we assume it's about 75pf/80pf (which is important compared to the TMS320F28377D input capacitance we have in front + the track capacitance).

Though we are able to have it working, I have concerns regarding min/max as we are performing our tests here at ambient temperature and we can't justify without further inputs from you our worst case analysis.

Best Regards,

Clément

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LM48580: LM48580 w. SMD inductor

March 26, 2019, 8:54 am
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Part Number:LM48580

Hi Team

my customer does have a capacitive based buzzer driver (charge pump) what boosts up the 3.3 V input voltage up to ~ 10 V

 

Now they looking for ways to increase the tone volume oft the buzzer. One approach would be LM48580. If they could generate 15 V instead of 10 V they assume this would work out for them.  Besides the tone voulume size is a very critical factor. therefor the solution size needs to be as small as possible

 

Ist the LM48580 able to work properley with following induktors:

 

 

Kind regards

Dierk Bronner 

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UC2625-EP: UC2625-EP General Questions, 2nd attempt to post

March 26, 2019, 12:08 pm
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Part Number:UC2625-EP

UC2625-EP

1) Would like to verify, the RC Oscillator 1-2 cycle dead time is only applied at HALL SENSORS transitions

2) Configured for four quadrant PWM , voltage control scheme, EA unity configured, EA+ control voltage with current sense PWM termination (Isense tied to PWM IN)

2-1) If current sense does not terminate PWM cycle what is the maximum duty cycle?

2-2) Is there any dead time between PWM cycles

3) Response time of internal fault over-current comparator to disable bottom side drivers?

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DRV8343-Q1: Gate resisters

March 26, 2019, 2:42 pm
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Part Number:DRV8343-Q1

Hi team,

I have some question about gate resister.

1. Can DRV8343 also drive FETs in parallel?

2. Does DRV8343 need gate resisters when driving FETs in parallel?

3. If gate resister is required, how should the gate resister be determined?

(Is it needed to consider the balance with the setting value of gate current etc.)

4. Will adding the gate resister affect the FET gate state monitoring function etc. of the IC?

Best regards,

Tomoaki Yoshida

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DRV8711: the voltage of SH1 and GH1 at Fast decay

March 26, 2019, 11:07 pm
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Part Number:DRV8711

Hi all

Would you mind if we ask DRV8711?
Could you refer to the attachment file?
(Please visit the site to view this file)

Kind regards,

Hirotaka Matsumoto

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DRV8306: Basic operation

March 27, 2019, 12:05 am
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Part Number:DRV8306

The Internal regulator is not output(DVDD 26pin) even though the VM is supplied(15V).

Would you please let me know the cause of that?

Actually, the load current of the main power supply is almost zero, and nFAULT is low at the time(immediately after power on).

I'd appreciate your help.

Best and Regards,

Sango 

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CCS/DRV8308: DRV8308 how to connect to run a bldc motor

March 27, 2019, 2:29 am
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Part Number:DRV8308

Tool/software: Code Composer Studio

HEELO

i read the data sheet and is a litle confuse to me
i have the drv8308 ic and i need to put a bldc motor to run on button1-> DIR 0
 and button2-> DIR 1

I gonna use a stm32F103RB micro controller to read an write in the registor
but witch pins i need enable for it work when a press the button.
when I press the button 1 what parameters do I have to activate?
button 1 is an input on my micro controller, which will then rotate
the motor in the DIR 0 direction.

I use the VSCODE with platformio  to program the stm32F108RB board 
I THINK this way when i press the button my micro controler active other output or send a hex comando to the register and motor RUN?

THANKS 

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DRV8711: Step-out state(stall) condtion without stall detection flag(STD bit)

March 27, 2019, 8:48 am
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Part Number:DRV8711

Hi all

Would you mind if we ask DRV8711?

We assume that it is not relation to DRV8711, however could you give us the advice?

Our customer uses DRV8711.

They have the troble which the motor is step-out state(stall) condtion without stall detection flag(STD bit=0).
During acceleration, it seems that it occurs step-out state(stall) condtion.
So, in this case, as the method, should we confirm follows?

1. Decreasing acceleration rate and start speed
2. Increasing current limitation
3. Increasing Fast decay rate

If you need some wave form, we will send you.

Kind regards,

Hirotaka Matsumoto

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DRV8818: Ask DRV8818 pin to pin solution, I want to make a PCB board that I can control 5V/12V/24V Step Motor by changing the driver IC

March 28, 2019, 12:24 am
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Part Number:DRV8818

Hello,

If I want to make a PCB that I can control 5V/12V/24V Step Motor by changing driver IC. Is there any pin to pin solution of DRV8818?  After remount the driver ic and change power voltage, I can control different step motor(different input voltage) 

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DRV8825: DRV8825 IC Heating

March 28, 2019, 12:43 am
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Part Number:DRV8825

Hello Everyone,

Thank you 

I have interfaced a 2-phase bipolar stepper motor with DRV8825 carrier board.

Testing Conditions

1. Vref is set to 1v for Coil current to 2Amp(set using POT on the board).

2. Step pin i am driving with 3KHZ PWM @50% duty cycle (Using Timer).

3. Ambient Temp is 25 Degree.

4. Stepping mode 1/32 Microstepping

4. The motor is running without Load i.e we have not connected any load to the shaft.

5. The heat sink is mounted

6. Decay Mode is set to Mixed decay.

7. I am Using STM32F7 for Step clock generation.

I have successfully interfaced and the motor and it is rotating but i am facing some issues.

Here are some issues that I am facing

1. The driver gets heated up after 2min of rotation and it shuts down because of inbuilt thermal protection.

2. I have set the stepping mode to 1/32 micro-stepping but the motor has huge vibration.

Please suggest me the possible ways to reduce the heating issue and vibration. How can i smoothen the motor rotation? 

Motor Details

operating Voltage 24-42v 

Current 2.8Amp/Phase 

Holding Torque 2.1nM

Thank You 

Abhishek

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DRV8844EVM: Split vs single supply

March 28, 2019, 12:48 am
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Part Number:DRV8844EVM

Hi TI,

Can someone explain why there's an option of using split supply and single supply?

I'd also like to know when it's appropriate to use a split vs a single supply.

Thanks.

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DRV8873: Standby current

March 28, 2019, 12:53 am
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Part Number:DRV8873

Hi,

I have breadboarded a DRV8873 to test the device driving a lock actuated by a solenoid. The peak current is 2.6A and steady current 2A, I choose this device because of the low RDS (the device itself is hand soldered on an adapter board, so there is no heat-sinking at all).

Things seem to work quite well, I am however surprised by the current drawn by the device: when not in sleep mode I have 50mA even when no load is connected. Is this normal ?

Thanks for any insight,

Marc

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