• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 29 subscribers
  • Views 178 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DRV110: Will the device switch to hold current if the peak current hasn't been reached?

John Griffith
Mastermind 21555 points
Part Number: DRV110

Hello,

My customer is wondering if they set the device up to have a 3A peak current for 4ms, and then want to switch to a 0.5A hold current, will the device make the switch even if the peak current hasn't been reached? Looking at the datasheet it doesn't seem to indicate anywhere the that switchover from TKEEP is related to anything other than teh capacitor value on the KEEP pin, but I want to clarify this. 

Thanks, 

John

  • 0
    TI__Mastermind 37683 points

    Hi John,

    The TKEEP time is set by the KEEP capacitor. Once the TKEEP expires, the current will drop to the value of the HOLD current configured via the external resistor. The driver will bring the current down to HOLD current once the TKEEP has expires regardless if the peak current was reached or not. If the initial current ramp up is very slow, TKEEP can be increase to allow more time for the current to reach the PEAK current.

    I hope this answers your question

  • 0 in reply to Pablo Armet
    TI__Mastermind 21555 points

    Hi Pablo,

    Yes it does. Sorry, one more follow up question. Does the hold current have to be 1/6 of the peak current? I believe the answer is no, but I think the line in the datasheet "In the 14-pin package, external setting of the HOLD current, IHOLD, works in the same way as the external setting for IPEAK but the current levels are 1/6 of the IPEAK levels for the same resistor setting." is confusing some people. 

    I think this is just saying that with the same values for peak and hold you have a 1/6 ratio in current. And if you ground both pins the defaults will have that ratio as well. 

    John

  • +1 in reply to John Griffith
    TI__Mastermind 37683 points

    Hi John,

    The statement can be a bit confusing so let me explain what it means. Basically what it is saying is that if HOLD and PEAK have the same external resistor, the ratio of I_PEAK/I_HOLD=6. However, I_PEAK and I_HOLD can be configured independently so the 1/6 current ratio is only true when both PEAK and HOLD resistors are equal or either one of them drops below 33.3kohm.

  • 0 in reply to Pablo Armet
    TI__Mastermind 21555 points

    This is exactly what I thought but my customer had kept increasing their peak current, above what they desire, to get the hold current they wanted. All while thinking the ratios had to be 1:6 of each other. Appreciate the super quick response. Have a great weekend Pablo!

    John

  • 0 in reply to John Griffith
    TI__Mastermind 37683 points

    John,

    You're welcome. Have a good weekend.