DRV2625: Motor Impedance

Dan Knodle

Part Number: DRV2625
Other Parts Discussed in Thread: DRV2624EVM-CT

The spec sheet for the DRV2625 states a maximum load impedance of 100pF. WHat happens if the impedance exceeds this value?

over 7 years ago

0 José Luis over 7 years ago

TI__Mastermind 20085 points

Hi Dan,

Welcome to E2E, thanks for your interest in our devices.
My colleague is going to review your question tomorrow.

Best Regards
Jose Luis Figueroa
Applications Engineer

0 Dan Knodle over 7 years ago in reply to José Luis

Prodigy 30 points

Great. i just realized I asked about impedance instead of capacitance, which is what I am interested in.

0 Kelly Griffin over 7 years ago in reply to Dan Knodle

TI__Genius 10512 points

The added capacitance will affect the transient response at the terminals of the LRA, and will impede proper operation of the resonance tracking algorithm.

0 Dan Knodle over 7 years ago in reply to Kelly Griffin

Prodigy 30 points

Thanks for the response. I cannot find the capacitance listed for LRA's in manufacturers data. Can I use a meter like the Agilent U1731C to measure the capacitance of the motor coil? I used this meter to measure the LRA on a DRV2624EVM-CT board and got the following results:

Resistance = 32 Ohms

Inductance = 192 uH

Capacitance = 132 uF

I cannot find a spec sheet for the ELV1036A Actuator. Is there a better method to determine the capacitance of an LRA?

0 Kelly Griffin over 7 years ago in reply to Dan Knodle

TI__Genius 10512 points

Hi Dan,

That is a pretty huge capacitance for a 1036 LRA. I haven't measured capacitance like this across the LRA, but I think you would need to use an impedance analyzer to measure capacitance with respect to frequency. Our driver can drive the ELV1036A LRA with no issue. I have used this in the past.

0 Kelly Griffin over 7 years ago in reply to Kelly Griffin

TI__Genius 10512 points

Dan,

Please let us know if you have any more questions or information about this thread. I will close it for now.

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DRV2625: Motor Impedance