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• TI Thinks Resolved

# CCS/DRV8876: Required power supply

Part Number: DRV8876

Tool/software: Code Composer Studio

Hi

Could you please give me some advice how to consider required power supply to work motor?f
I attaches simple figure.

Motor's specification is following.

VM=24V
Output current = 0.3A (while steady operation)
Peak current = 0.9A (At start up motor)

I want to understand how the peak current of motor (0.9A in this case) should be considered.

What is required power in this case?

BestRegards

• Hi na na78,

A rough estimate is ~50W, but this could vary depending on:

power supply voltage variation,
motor startup current variation,
additional system current consumed by other components not shown
PWM frequency if used

The equation used was (VM * Istartup)/.50 system efficiency =~43W. This assumes the motor can be stalled leading to 0.9A DC and a conservative system efficiency estimate of 50%.

Best Regards,
Rick Duncan
Motor Applications Team

• In reply to Rick Duncan:

Hi Rick

You assume the current flows at motor stalled condition would be the same as startup.
I understand that if stalled current is 0.9A, we should consider it to obtain total power.

Do you think we should consider stalled current?  I got startup current, but I did not still get stalled current.

Even if the startup current flows in short amount time, should we consider 0.9A as a current to calculate total power?

BestRegards

• In reply to na na78:

Hi na na78,

It is difficult to answer this question because the use profile can affect how long startup/stall current occurs.

Because I do not know the use profile, I assumed stall current.

If voltage drops on VM do not affect the rest of the system and the startup current time is known, the power supply wattage can probably be reduced.

Best Regards,
Rick Duncan
Motor Applications Team