DRV110: Problems selecting resistors for Ihold and Ipeak

Larry Brazis

Prodigy 60 points

Part Number: DRV110

Hi TI,

We want to set the DRV110 for a peak current of 1.0A, and hold current of 0.3A.

We are experiencing difficulty selecting the workable values using the equations.

Can you please recommend the correct values for Rpeak, Rhold, and Rsense?

We are on a fast track to complete our printed circuit board layout and your prompt reply would be appreciated.

Thanks!

Larry

over 5 years ago

0 Grant Falkenburg over 5 years ago

TI__Intellectual 1965 points

Hi Larry,

Let me contact the expert for this part. You can expect a response by 10/25/19.

Best regards,

Grant

0 Costin Cazana over 5 years ago

TI__Expert 4940 points

Hi Larry,

The voltage across Rsense :

Peak: 30mV<Vsense<900mV

Hold: 5mV<Vsense<150mV

The range min is comparator detection threshold, max is the saturation. Recommendation is not to get too close to these values

For the target Ipeak and Ihold:

0.03ohm<Rsense<0.5ohm

For Rsense=0.25ohm : Rpeak=240kohm, Rhold=133kohm

For Rsense=0.3ohm : Rpeak=200kohm, Rhold=111kohm

Regards,

Costin

0 Larry Brazis over 5 years ago in reply to Costin Cazana

Prodigy 60 points

Thank you for the information. I used a 0.25 ohm sensing resistor and the set the pots on the eval board per your recommendation. I hold was 0.3 amps but I peak would not go above 0.6 amps. Today I will try to find the problem. Do I need to isolate the on board potentiometer form the IC circuit when I set it with my meter?

Do you believe that I need to set Rsense to a higher value?

Thank you,

Larry

0 Costin Cazana over 5 years ago in reply to Larry Brazis

TI__Expert 4940 points

Hi Larry,

0.25ohm is ok, very likely Ipeak is limited by solenoid supply voltage headroom:

Ipeak_set*Rsolenoid>Vsupply.

Regards,

Costin

0 Larry Brazis over 5 years ago in reply to Costin Cazana

Prodigy 60 points

Hi Costin,

My solenoid coil measures 12 ohms. To achieve a 1 amp peak current the supply voltage must be increased to 24 volts or so. Can you explain why the supply voltage needs to be increased and what could be adjusted to achieve a 1 amp peak current using a lower supply voltage?

Thank you,

Larry

0 Larry Brazis over 5 years ago in reply to Larry Brazis

Prodigy 60 points

We are still on a fast track and our PCB routing is scheduled to begin on Monday Nov 4th! Can we have a conference call today to discuss and resolve this open issue?

0 Costin Cazana over 5 years ago in reply to Larry Brazis

TI__Expert 4940 points

Hi Larry,

Of course, my contact info:

costin.cazana@ti.com

408-745-2819

Regards,

Costin

0 Larry Brazis over 5 years ago in reply to Costin Cazana

Prodigy 60 points

Hi Costin,

I can't reach you by phone because there is no answer. Can you answer my latest questions?

Thanks,

Larry

0 Costin Cazana over 5 years ago in reply to Larry Brazis

TI__Expert 4940 points

Hi Larry,

Since the system issue has been identified, I'll close this thread.

Regards,

Costin

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DRV110: Problems selecting resistors for Ihold and Ipeak