DRV8805: use it in parallel

Howard Zou

Genius 12365 points

Part Number: DRV8805
Other Parts Discussed in Thread: DRV8711, TIDA-00872

Hi,

my customer need 24V, 3A unipolar stepper motor driver.

Since DRV8805 can only support 2A with single channel on. And 1A per channel when four channel on.

So I think I can use 2 DRV8805 in parallel to achieve 3A current rating.

There are two options:

1. use 2 channels within one drv8805 in parallel, but the datasheet doesn't tell me how much current it can handle when 2 channels are on.

2. Use channel 1 of two drv8805 in parallel, now it should be able to handle totally up to 4A, but I'm not sure if it's okay to use 2 drv8805 in parallel in such way.

over 6 years ago

0 Rick Duncan over 6 years ago

TI__Guru** 114905 points

Hi Howard,

Two DRV8805 are not designed to be operated in parallel. First, the current when two channels are on can be estimated to be square root (2A squared/number of active channels), or 1.4A. If one device overheats, the other may enter overcurrent shutdown.

Has the customer considered driving the stepper in a bipolar configuration? The DRV8711 in bipolar mode would be able to drive the stepper.

Another option is to configure the DRV8711 in unipolar mode with external circuitry. TIDA-00872 shows how to add external circuitry to drive a unipolar motor.

0 Howard Zou over 6 years ago in reply to Rick Duncan

TI__Genius 12365 points

Rick,
why do we need to supply 12V to DRV8711 in TIDA-00872 ? Can we directly provide 24V to both DRV8711 and external MOSFET?

0 Rick Duncan over 6 years ago in reply to Howard Zou

TI__Guru** 114905 points

Hi Howard,

12V was chosen to avoid violating the Vgs of Q3, Q4, Q9 and Q10. Also 12V provides the proper voltages back to the DRV8711 to indicate proper operation.

24V could be used with 30V Vgs FETs, or by adding additional circuitry to reduce the voltage at the gate of the FETs.

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DRV8805: use it in parallel