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DRV110: reset in cold temperature.

avraham Kurtz
Prodigy 140 points
Part Number: DRV110

Hello 

for some reason when i lower the Vin from 28 to 24V in cold temperature of -30deg  during holding current state the DRV110A goes in to reset and keeps of going in to continuous cycle of startup current  to hold current to start up to hold. above 24V there is no problem.

any ideas ?

the enable pin is floating so it is activated from the internal pu.

  • 0
    TI__Mastermind 23421 points

    Hey Avraham,

    Can you get a scope capture of the supply voltage and current here, and at a higher temperature? I'm wondering if the low temperature is affecting your power supply as well and that change is carrying over into the DRV110 performance.  

    Beyond that, check the datasheets of some of your external components such as capacitors and see if they need to be de-rated based on the temperature.

    Also is that -30°C or F? I guess it doesn't make much difference, just curious. 

    Best,

    Jacob 

  • 0 in reply to Jacob Thompson
    Prodigy 140 points

    hi

    the problem seems to be because of the Rs value the value on Rin seems to be on the range 5-6V. is the input stage really a zener ? it doesn't act like a proper zener  / my supply voltage is between 22-29V ive put had a 6.47K for rs and changed to 5.3K and am getteing better results but  when the temperature fall bellow room temperature i get an input voltage of 5-8V on the Vin (after rs) which makes no sense (the !q current must be higher in cold temperature ?).   

  • 0 in reply to avraham Kurtz
    TI__Mastermind 23421 points

    Avraham,

    Any progress on this? 

    Is your 22-29V DC?  If so, just want to confirm your diagram follows this schematic:

    Then for approx. 24V we recommend a 9kΩ or 13kΩ resistor for Rs.  See the below image from the datasheet for how to calculate the RsMAX and RsMIN 

    Best,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 140 points

    thank you Jacob for your reply 

    According to the equations the Rs resister is between 4-5K.

    After reading lots of post on this part and much testing on my circuit, is see that this part is really not made for one single supply (with a large voltage range) and like many other drivers should have a separate  power stage supply that can have a large range and a separate constant supply for the Vin (control supply ) about 12V .

    After implementing this to my board I see the hold current stays constant and steady and not effected by the change of the Power stage voltage supply (22-29). I think you should mention this in your datasheet .

    Also the datasheet should be updated about the Zener characteristic in cold temperature.

    Thank you

    Avraham Kurtz

  • 0 in reply to avraham Kurtz
    TI__Mastermind 23421 points

    Hey Avraham,

    Glad to hear that a constant supply for VIN solved the issue.  I'll look into getting our datasheet updated.  Thanks!