DRV8256: How to drive two unidirectional brushed DC motors

Markus Neumair

Part Number: DRV8256
Other Parts Discussed in Thread: DRV8874, DRV8837

Hello,

can you please provide a short example on how to drive two unidirectional brushed DC motors using the DRV8256?

I guess the circuit should be similar to the one of the DRV8874 (Section "8.2.2 Alternative Application" in the datasheet). Anyway, the DRV8256 has no "Independent Half-Bridge" mode. Therefore, i guess it's neccessary to turn current regulation off by connecting Vref and DVDD, correct? (Otherwise, the chip would turn off e.g. motor 2 if motor 1 draws a current higher than the one defined by Vref)

Is it possible to use the DRV8256 as a two channel high-side driver to simplify external current measurement or is there a drawback with that?

Best regards,

Markus

over 2 years ago

0 Pablo Armet over 2 years ago

TI__Mastermind 37683 points

Hi Markus,

Please read section 7.3.2 od the DRV8837 datasheet (https://www.ti.com/lit/ds/symlink/drv8837.pdf?ts=1635269203097&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDRV8837) to learn how to configure independent half-bridge control. Even though this is for the DRV8837, the method can be applied to the DRV8256.

0 Markus Neumair over 2 years ago in reply to Pablo Armet

Prodigy 155 points

Hi Pablo,

I had a look at the mentioned datasheet and realized that I forgot to mention that I plan to use the DRV8256P. Furthermore, I do not need the internal current regulation feature.

Unfortunately, the logic tables of both chips differ. Therefore the following question still remains:

Is it possible to use the DRV8256 as a two channel high-side driver to simplify external current measurement (low-side) or is there a drawback with that?

+1 Pablo Armet over 2 years ago in reply to Markus Neumair

TI__Mastermind 37683 points

Hi Markus,

Please disregards my previous comment. The DRV8256 can drive two unidirectional BDC drivers in either high-side or low-side configuration. IN1 controls OUT1 and IN2 controls OUT2. If you don't need current regulation, VREF can be tied to DVDD. This will set the current regulation to the highest value of 6A. Below is a diagram showing how to configure the two motors in high-side configuration.

Motor drivers

Motor drivers forum

DRV8256: How to drive two unidirectional brushed DC motors