DRV8323: Separate VM to reduce power dissipation/DRV8353 compatibility?

Aidan Fransen

Part Number: DRV8323
Other Parts Discussed in Thread: DRV832X

Hi there,

I have a design using the DRV8323S which is working well. However, I notice that while in operation it gets fairly warm especially for voltages >36V (presumably from the internal linear regulators), so I was wondering if the VM input of the chip could be powered by a different regulated supply (such as 12V..). It seems that this is possible on the DRV8353S, but the DRV8323S datasheet is a bit unclear as to whether VM or VDRAIN is the reference for the charge pump.

This would also allow for compatibility with the DRV8353S which I am considering using for the future (as I may need to driver higher voltage motors).

To summarise; for a motor supply voltage of 40V, can VM be supplied with 12V?

Regards,

Aidan

over 2 years ago

+1 Davis Jackson over 2 years ago

TI__Expert 3020 points

Hi Aidan,

The DRV8353S does have the option for split power supply, per this technical note: https://www.ti.com/lit/an/slvae45/slvae45.pdf. However, the DRV8323S does not have this split power supply capability. The VDRAIN pin serves as the high side FET drain sense input, and it is used for VDS monitoring as shown in section 8.3.1.4.4 MOSFET VDS Monitors in the DRV832x datasheet. Section 8.3.1.4.5 also notes that VM is the reference for the charge pump, and VDRAIN must not drift far from VM. So, VM must be the same as the motor voltage.

Best,

Davis

0 Aidan Fransen over 2 years ago in reply to Davis Jackson

Prodigy 20 points

Ok that answered my question, thanks for the quick reply

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DRV8323: Separate VM to reduce power dissipation/DRV8353 compatibility?