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UC2625: SPEED-IN threshold

February 28, 2018, 6:50 am
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Part Number: UC2625

Hello,

I am using the UC2625 and from what I understood in the datasheet and the block diagram is that once SPEED-IN passes a certain threshold, which should be around 250mV, the device should inhibit any change in direction. In my application I have my inputs setup for Pin 12 (PDC) to be high while Pins 13 and 14 (PDB & PDA) are low. When I set SPEED-IN to the max threshold which should insure no change in direction and change the DIR pin from a 1 to a 0 with no change in my other inputs setup I see a change in my outputs (PDC goes low, PDB goes high and PDA stays low). Shouldn't the outputs not change since SPEED-IN is above the threshold that should inhibit any changes in DIR? Or is there something I am missing ?

Thank You,

Youssef

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RE: DRV8305-Q1: Charge pump behavior after EN_GATE is set low

March 8, 2018, 5:17 pm
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Hi Paul,

When EN_GATE transitions from high to low, the charge pump will stop switching, and the VCPH voltage will slowly dissipate. This is demonstrated in the scope capture below:

If you look at the functional block diagram or typical application diagram in the datasheet, you will see the the VCPH capacitor should connect between the VCPH pin and PVDD. Therefore, the voltage on the VCPH will depend directly on the PVDD voltage. Under normal operating conditions, VCPH will attempt to regulate to around 10V above PVDD, and when EN_GATE is low, will dissipate back to the level of PVDD.

Is this question related to an issue you are observing in your circuit, or are you just attempting to clarify device behavior?

Thanks,

Garrett

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RE: DRV8305: EN_GATE reset pulse time

March 8, 2018, 5:22 pm
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Hello Riveros-san,

Thank you for your answer. Could you teach more detail?
Does the '1us' include margin of temperature characteristics and individual variation?
How long maximum time to keep low before making it high for reset?
Is this maximum time '1us'?

Best regards,
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RE: DRV8305-Q1: Charge pump behavior after EN_GATE is set low

March 8, 2018, 5:30 pm
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I'm trying to clarify device behavior. Thank you!
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DRV8305-Q1: Charge pump behavior after EN_GATE is set low

March 8, 2018, 11:01 am
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Part Number: DRV8305-Q1

The gate driver IC is operating in a normal, steady state mode. What happens to the VCPH voltage when the EN_GATE transitions from high to low as a result of the microprocessor that controls the gate driver IC detects an undervoltage?

Does the VCPH pin become an open circuit?

Does the voltage on the VCPH pin depend on the driver IC's PVDD voltage in the case where the PVDD voltage is the voltage that experiences the undervoltage event even when the EN_GATE transitions from high to low?

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Sensorless BLDC driver

March 8, 2018, 6:09 pm
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Hi all!

we may need your support in choosing the right components for a sensorless bldc pump controller.

The key fact and goals are:
-   24VDC pumps
-   best case we can cover 50 – 220W pumps
-   smooth characteristic, sinusoidal could be a benefit
-   price sensitive product
-   10k/year


I found some drivers on the ti homepage:
http://www.ti.com/motor-drivers/brushless-dc-bldc-drivers/overview.html
But which one could fit the best for our goals.

Thank you!

Thomas

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RE: DRV8816: Is it possible to use two half-bridge in parallel?

March 8, 2018, 7:45 pm
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Hi Rick Duncan,

Thanks for your suggestion, we will consider these chip as an alternate.

Best Regards

  

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DRV8308: Smart gate driver

March 8, 2018, 9:48 pm
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Part Number: DRV8308

Hi

I believe DRV8308 has smart gate driver function.

Is it right?

BestRegards

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RE: DRV8812: Power supply VMA and GND are shorted

March 9, 2018, 1:52 am
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Dear James san

Another phenomenon occurred today another one.

This also occurred at 15 ℃ environment.

I will attach the findings.

■phenomenon
Motor current larger than set current flowed

When FEED was performed at 20 second intervals, abnormal motor current flowed after 20 sheets.
When printing 100 sheets, only 2 pieces of motor current abnormality occurred.
There is no problem in 30 ℃ environment.

■Device seal
I bought a new device from another trading company and tested it
NG:「DRV8812 TI 72I C1V1 G4 」　←　Backfeed NG, short NG, motor current abnormality occurrence
No problem:「DRV8812 TI 3BI C63K G4 」　←　Purchased from another trading company

Various problems occur when testing in the 15 ° C environment.
Backfeed error, device short, motor current abnormality

Please comment on what is affecting.

Regards Aoki(Please visit the site to view this file)

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DRV8812: Power supply VMA and GND are shorted

March 4, 2018, 6:54 pm
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Part Number: DRV8812

We are implementing DRV 8812 on a mobile printer and evaluating it.

When printing about 10 sheets in 15 ℃ environment, the printer suddenly stopped.

After confirming, it was 2 Ω between VMA and GND.

Another one got 15 Ω between VM and BOUT 2

Power supply voltage VM = 15.5 V
Motor current = 290 mA or 400 mA

There is no overvoltage in the VM.

he following terminals are controlled during printing.

nRESET,nSLEEP,AENBL,BENBL

VM supply

Backfeed start → valid

Stop backfeed → disable

Feed start → valid

FEED stop → disabled

If these signals change frequently, is there a possibility of device short circuit?

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RE: DRV3205EVM: Need acces to schematic, CAD and BOM for DRV3205EVM

March 9, 2018, 4:49 am
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Ok, perfect!
Best Regards,
Robin
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RE: BLDC better motor driver needed

March 9, 2018, 5:36 am
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Hi Christian,

There is one device with internal FETs and no ability to directly control the halls, and a second device that can control the halls but no internal FETs.

The DRV8312 with internal FETs can meet the current and voltage requirements. External logic is required to convert the hall signals into PWM inputs.

The DRV8320H has a 1x PWM mode to directly use the halls, although external FETs are required. The benefit of external FETs is you can decide what RDSon to use.

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BLDC better motor driver needed

March 9, 2018, 1:45 am
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Hello all,

We are in search for a new motor driver replacing L6235 from ST for a brushless application.  

The driver should have internal FETs. And also take care of the hall signals (also be a controller). The external uC controlling the application should only care about direction and duty cycle. Same as L6235 provides. The ST driver to be replaced has too high RDSon. Thats the motivation for replacement. Except for this the driver is well suited. 

The interface can be any time. Parallel, I2C, SPI. This is not relevant. What is of high relevance is that the FETs are internal and that the driver is also a controller (takes care of the hall signal inputs)

It should accept a bridge voltage of at least up to 36V or if no option exist 24V can be a lesser alternative.

Can you guys recommend any BLDC driver for this application? Does TI have any at all that come close to this?

Extra info: The motor it should drive is the low inductance EC-i 30 from maxon motor.

Best, Christian

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RE: DRV8703-Q1EVM: Regarding Vreff and driver connect to external micro

March 9, 2018, 5:50 am
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Hi Kallepalli,

Please refer to the datasheet for the functionality of each pin. Removing the VREF connection changes the chopping current.
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DRV8703-Q1EVM: Regarding Vreff and driver connect to external micro

March 9, 2018, 5:23 am
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Part Number: DRV8703-Q1EVM

Hai,

Thanks for responding my previous forums.

As per your suggestion I removed resistors between micro and driver IC of IN1 and IN2 pins, because I want to drive the motor with external micro by providing PWM to IN2.

Before it was working fine, now i removed resistor between micro and driver IC of Vreff pin. Now there is no moment in motor.

And I can't replace that resistor back.

So, give me some information so that motor drives previously.

And my total aim to control the motor through all the 14 pins provide on the evaluation board. 

And I also want to read the status through SPI.

All working fine before removing of Vreff resistor.

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DRV8846: Accuracy of pull up & pull down resistors on tri-level input pins

March 9, 2018, 6:11 am
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Part Number: DRV8846

Hi, Team

Do we have accuracy data of accuracy of pull up & pull down resistors on tri-level input pins?

Thank you.

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RE: DRV8846: Accuracy of pull up & pull down resistors on tri-level input pins

March 9, 2018, 6:43 am
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Hi Alvin,

What is the concern about the accuracy of the resistors?

The pullup and pulldown resistors are designed to track each other, creating a typical voltage of 1.1V when floating.
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RE: DRV8308: Smart gate driver

March 9, 2018, 7:03 am
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Hi na na78,

Yes, the DRV8308 is considered to have smart gate drive.
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RE: Sensorless BLDC driver

March 9, 2018, 7:25 am
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Hi Thomas,

Please look at the DRV832x series of devices. With a mcu and FETs, these devices can control a sensorless BLDC.

The BOOSTXL-DRV8320H is available for evaluation.
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RE: DRV8303: DRV8303 GVDD drops down to 2.3V

March 9, 2018, 9:45 am
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Hi Grady,

What is the VM voltage in the image provided?
How high was VM when the GVDD voltage dropped?
Can you provide a schematic of the DRV8303 and the components around it?
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