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DRV104: Valve Driver unexpected results

Todd Jonas
Prodigy 10 points
Part Number: DRV104
Other Parts Discussed in Thread: STRIKE, DRV110, DRV8846

We are using the DRV104PWPR chip and trying to drive a 8watt air solenoid with a 24VDC turn on for 8 ms and then drop the voltage to about a 40% duty cycle.  I have the circuit diagram attached and it is setup like the datasheet example in Figure 17.  When we have no load connected, the output acts as expected, where we have 24V for about 8 ms then it chops to an average of 9.7VDC.  But when I connect a load, the voltage during chop reduced to an average of 2.4VDC.  Do you have any idea what can be causing this?

       

  • 0
    TI__Mastermind 22710 points

    Hey Todd,

    Is this on our EVM or your own board?  Nevermind, apparently we don't have an EVM for this part. 

    Does your power supply have sufficient current for the load?

    Give me another day to look into this as it is a very old part. 

    Is this a new design? If so I can recommend a newer part for you instead if you can give me the load current (peak/continuous).

    Best,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 10 points

    Hello Jacob,

    I changed to a 5A power supply just to be sure and have the same result.  It is a new design and if there is a different part that you recommended we would be happy to look into it.  We will be designing a new coil for the solenoid and our end goal will be to have a 2A peak current with a 1A hold current.

  • 0 in reply to Todd Jonas
    TI__Mastermind 22710 points

    Hey Todd,

    Apologies busy day, haven't had time to dig into the DRV104 datasheet for this yet. 

    So for a 24V / 2A peak / 1A continuous motor driver, I would recommend DRV8231A.  It's a 35-V, 3.7-A H-bridge motor driver with integrated current regulation & current-sense feedback.  You will need to manually do the PWM change after 8ms with your microcontroller, but its a much smaller and cheaper device than DRV104.  Here's the EVM you could easily use to try it out - https://www.ti.com/tool/DRV8251AEVM 

    If you want independent 1/2 bridge control so the other side of the load can be connected to GND or VM, I would recommend the DRV8876

    Either way, see our application note Using DRV to Drive Solenoids.  

    Best,

    Jacob

  • 0
    Prodigy 10 points

    Jacob,

    Thank you for the information.  We will check into these other driver options.  In the meantime, is there any indication what could be going on with our DRV104 circuit that is dropping its output only when a load is connected?

  • 0 in reply to Todd Jonas
    TI__Mastermind 22710 points

    Hey Todd,

    Hmm could be due to insufficient bulk capacitance, could you try increasing C1?

    Do you have a smaller load you could test with, to see if any load causes it or only a certain level of load?  

    Also have you tried this on multiple boards and devices to rule out device damage (ESD strike?) or board issue? 

    Regards,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 10 points

    Hello Jacob,

    I am going to try your suggestions to increase C1, reduce load, and try a second chip, but I think we are going to look more into the DRV110 chip as we would like to drive the current.

    We are trying to develop a valve driver that can power up and drive a solenoid with the same 24VDC signal.  In this board we did not plan to have a programmable MCU. 

    Is it possible to power up the DRV110 and enable it at the same time? 

    If it's possible, I assume there would be some short startup delay, what would that time be? 

    With the DRV110 evaluation module (SLVU686B) would it be possible to modify the module to be able support 24VDC power input and drive up to 2 amps?

  • +1 in reply to Todd Jonas
    TI__Mastermind 22710 points

    Hey Todd,

    Todd Jonas said:

    Is it possible to power up the DRV110 and enable it at the same time? 

    If it's possible, I assume there would be some short startup delay, what would that time be? 

    Yes, it is possible to power up the DRV110 motor driver and enable it simultaneously. The DRV110 motor driver can be enabled or disabled through its ENABLE pin.  The delay will be tD (Start-up delay) of 50us, and likely some device Power-on time that I'm not seeing in the datasheet.  I suspect the Power-on time would be in the scale of 1ms or 2ms, as that's what I am finding in the DRV8846 data sheet that was released a couple of years after DRV110.  

    Todd Jonas said:
    With the DRV110 evaluation module (SLVU686B) would it be possible to modify the module to be able support 24VDC power input and drive up to 2 amps?

    Yes, that should work fine! 

    V_DC supports 7-48V.  However, Q2 the FET only supports 1A.  I suggest replacing this FET with one capable of 2A for your application.  This FET might work, it is same footprint and drive voltage but capable of 4A continuous:  IPD95R2K0P7ATMA1

    Q2  497-2483-1-ND MOSFET N-CH 600V 1A DPAK

    Best,

    Jacob