drv8825

manglesh

Other Parts Discussed in Thread: DRV8825

Hi!
i want to design a stepper motor drive using drv8825 IC. The driver will just have step, direction and enable in input and power supply seperate of 24v. The controller will run on seperate power supply. Will it be possible to design such driver and if yes, what is the way to do it.

over 12 years ago

0 RE over 12 years ago

TI__Mastermind 20985 points

Hi Suraj, this sounds like a very typical application. Are you mostly wondering which microcontroller to use?

Best regards,
RE

0 Ryan Kehr over 12 years ago in reply to RE

TI__Guru 55615 points

Suraj,

We have already done the work for you! :)

Please see the EVM link below with example firmware and hardware files:

http://www.ti.com/tool/drv8825evm

0 manglesh over 12 years ago in reply to Ryan Kehr

Prodigy 130 points

thanks for rply sir..!!

I already referred it and it is very nicely documented but the schematic is not properly visible. i have a controller which runs on separate power supply other than driver's power supply. And the EVM has on board controller. I m confused whether the given design will work under such condition or not. and what is the wattage of the resister R5 and R6 ?

0 RE over 12 years ago in reply to manglesh

TI__Mastermind 20985 points

Suraj,

You're right that the schematic in the back of the User's Guide isn't very readable--we'll improve that soon. You can get a high quality version of the schematic within the software pack: http://www.ti.com/litv/zip/slvc342a (see the PDF in subdirectory "EVM Related"). The MSP430 power supply is 5V, whereas the motor voltage (VM) is 8V to 45V.

A BOM Excel file is also there, which shows that R5 and R6 are rated to 2W.

Best regards,
RE

0 manglesh over 12 years ago in reply to RE

Prodigy 130 points

RE,
Thanks sir! for the software pack. what if R5 and R6 are of 3W but the resistance is same 0.2 ohm. is it necessary to have same ground level to micro controller and drive? Which parameter is related for current setting?

thank you sir!

0 RE over 12 years ago in reply to manglesh

TI__Mastermind 20985 points

The DRV8825 controls current through the motor winding based on VREF and RISENSE, in the equation on datasheet Page 9. 3W resistors should work fine (since current would need to reach 15A for them to burn 3W). The microcontroller GND should be a similar potential to the DRV8825 GND, so that the input voltage VIH is satisfied.

Best regards,
RE

0 manglesh over 12 years ago in reply to RE

Prodigy 130 points

RE sir!
Hey.! i can use optocoupler in my design as the ground level of driver and controller are not same. Thanks for the guidance sir.!! I am working on it. And get back to you with the result.

regards,

manglesh

0 Shalom Lavi over 12 years ago in reply to Ryan Kehr

Prodigy 30 points

Hey,

I started to design a step motor controller using DRV8825 component. I wonder, I have one power supply of 24V/2A. Can I use it for low voltage 3.3V/5V for component and a voltage VM motor? in all design I saw capacitor 100Uf for VM does it matter which kind of capacitor i use?

Thanks for your help

Shalom Lavi

Orbotech Ltd.

Israel

0 Wilson Zuo over 12 years ago in reply to Shalom Lavi

TI__Mastermind 26065 points

Hi Israel

You can use that power and make sure all inputs logic voltage should <= 5.25V, and Vref<=3.3V.

About the VM cap, you can use a 100u~470u aluminum electrolytic type in parallel with a 0.1u~1u ceramic capacitor with low ESR.

Thanks.

Wilson

0 Shalom Lavi over 12 years ago in reply to Wilson Zuo

Prodigy 30 points

Hi Wilson

Thanks a lot for your help, I will be in touch.

Shalom

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