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DRV8231A: Solenoid and Motors

Dharmesh Joshi
Expert 1815 points
Part Number: DRV8231A
Other Parts Discussed in Thread: DRV8231, DRV8220, DRV8242-Q1, DRV8256, DRV8876-Q1

Tool/software:

Hi,

We have been using the DRV8837CDSGR in the past, and due to our voltage increase to 12.6V, we will need to use the DRV8231A.

What is the difference between the DRV8231A and the DRV8231?

We aim to use the DRV8231A for the following two separate applications:

1. **Latching Solenoid:** On the PCB, there would be a requirement for 8 of these. Is there a possibility we could incorporate some type of enable so that only the correct device is controlled by a common IN1 and IN2 signal? With the existing design, we do have 8 separate enable signals available. I guess, in the worst case, I could use one of TI's GPIO buffer ICs.

2. **A small 12V pump rated to 1.5A at max flow:** In the past, we have used a standard driver with protection (IXDI630MYI) for this, but since we will be using the DRV8231A in our inventory, I would like to know if this DRV8231A can also be used for that. This pump has an inductive motor, but bidirectional control is not necessary. Therefore, I guess IN2 can always be low and IN1 can be toggled like an enable? In addition, should the pump's negative wire be connected to one of the outputs connected to GND, or should it be connected directly to the GND?

Thank you.

  • 0
    TI__Mastermind 22050 points

    Hello,

    Dharmesh Joshi said:
    What is the difference between the DRV8231A and the DRV8231?

    The A-version doesn't need a bulky sense resistor to measure motor current.  Just a small bias resistor (ex. 0402 or whatever size you want)

    Dharmesh Joshi said:
    1. **Latching Solenoid:** On the PCB, there would be a requirement for 8 of these. Is there a possibility we could incorporate some type of enable so that only the correct device is controlled by a common IN1 and IN2 signal? With the existing design, we do have 8 separate enable signals available. I guess, in the worst case, I could use one of TI's GPIO buffer ICs.

    Hmmm I would think that with some creativity and logic gates that could be cut down to 3 signals (2^3 = 8) to basically address them in binary.  But you would basically be making your own buffer IC or I2C GPIO expander, so yeah might not be the easiest way.  

    Dharmesh Joshi said:
    2. **A small 12V pump rated to 1.5A at max flow:** In the past, we have used a standard driver with protection (IXDI630MYI) for this, but since we will be using the DRV8231A in our inventory, I would like to know if this DRV8231A can also be used for that. This pump has an inductive motor, but bidirectional control is not necessary. Therefore, I guess IN2 can always be low and IN1 can be toggled like an enable?

    Yes, that would work! 

    Dharmesh Joshi said:
    In addition, should the pump's negative wire be connected to one of the outputs connected to GND, or should it be connected directly to the GND?

    You'll connect the pump's negative wire to the motor driver, which will be connected to GND.  Though I suppose it should work the same either way, I recommend connecting to the driver. 

    The only slight downside of doing it this way is you're basically "wasting" half of the FET area inside of the device by not using it.  If you used a motor driver with the feature "Independent 1/2 bridge control" then you could parallel the two outputs and use them both to drive your load like in the image below from the DRV8220 datasheet.  DRV8220 is 18-V, 1.76A peak for full-bridge mode (what you described with 8231A) or 3.52A peak with the outputs paralleled like in the images below. Paralleling the FETs halves the resistance, thus allowing double the current for the same thermal performance.

    Best,

    Jacob

  • 0 in reply to Jacob Thompson
    Expert 1815 points



    Thank You for your reply.

    So, in regard to sensing the current, is it not possible to simply provide a Vref, e.g. 2.5V and monitor the output voltage using an ADC, or do you need an amp?

    Does TI offer something similar to this IC but with an additional Enable? If not, I can create a 3-bit binary driver, ideas i2C GPIO, as suggested.

    When driving a small pump using the DRV8231, do we need to use any additional protection circuit, as we had to use diodes and fuses with IXDI630MYI?

    Yes, we are wasting half a FET, but ideally, we want to consolidate our BOMs so that we have common parts across all our PCBs; in addition to that, the price for DRV8231 is far less than IXDI630MYI, therefore even with the FET being wasted, it saving us an overall cost on the PCB.

    In addition to this, would there be any issue if this device were to be used as an LOAD switch as well?

    In regard to the diagram, so with the DRV8220 , can both outputs a high voltage at the same time?

  • 0
    Expert 1815 points

    Dear

    Any update my additional questions

  • 0 in reply to Dharmesh Joshi
    TI__Mastermind 22050 points

    Oops apologies Dharmesh, this got lost. 

    Dharmesh Joshi said:
    So, in regard to sensing the current, is it not possible to simply provide a Vref, e.g. 2.5V and monitor the output voltage using an ADC, or do you need an amp?

    Using DRV8231A yes, that is exactly how it works.  Just need an ADC to monitor IPROPI.  

    Dharmesh Joshi said:
    Does TI offer something similar to this IC but with an additional Enable?

    Hmm the Hardware version of DRV8242-Q1 could be a good option, the DRVOFF pin enables/disables the outputs.

    Or if you're just looking for redundancy to setting IN1+IN2 both LOW, then maybe setting VREF to 0V would be an option?  Or setting nSLEEP low on a device with nSLEEP such as DRV8876-Q1 or DRV8256.  

    Dharmesh Joshi said:
    When driving a small pump using the DRV8231, do we need to use any additional protection circuit, as we had to use diodes and fuses with IXDI630MYI?

    No, you should not.  With sufficient Bulk Capacitance (see Bulk Capacitor Sizing for DC Motor Drive Applications) it will keep the VM voltage below dangerous levels.  The only extra circuitry you might want could be ESD protection if the output connectors might be touched by the user 

    Dharmesh Joshi said:
    In regard to the diagram, so with the DRV8220 , can both outputs a high voltage at the same time?

    Yes absolutely! 

    Dharmesh Joshi said:
    In addition to this, would there be any issue if this device were to be used as an LOAD switch as well?

    Generally no issue.  Just make sure the device can handle the RMS current, as often the peak current and continuous current our device can handle is very different.  And of course TI has dedicated load switches as low as $0.30 for https://www.ti.com/product/TPS22811#order-quality (there might be a better option for you), but I understand the desire to consolidate BOM.

    Best,

    Jacob 

  • 0 in reply to Jacob Thompson
    Expert 1815 points

    Thanks for the reply 

    Great, i will connect it to the ADC, this would give a good indication that the pump/ motor is working.

    We aim to place about 8 of them on a different PCB design, so ideally, we would like to control them all with a common Signal + Enb for each device.

    Well, the pump is 12V max, about 1A. The connector is used to connect a long wire with the pump connector, and we will simply insert the pump into that connector; therefore, would we need ESD protection for that?

    Well, we sometimes need an odd load switch in our design, but to keep our BOM list to a minimum and cost done, I was thinking that I could simply use the DRV8231A and keep one input forced to GND. 

    We aim to use the SOIC version, but with the exception of connecting the GND pad to copper pours, how can we work out the heat dissipation and how long can we run a motor continuously?

  • 0 in reply to Dharmesh Joshi
    TI__Mastermind 22050 points
    Dharmesh Joshi said:

    We aim to place about 8 of them on a different PCB design, so ideally, we would like to control them all with a common Signal + Enb for each device.

    Hmmm potentially you could use a digital signal for VREF and set it LOW/HIGH (0V / 3.3V), or if a lower voltage was desired put that through a resistor divider to lower it but still digitally control it.  

    Dharmesh Joshi said:
    Well, the pump is 12V max, about 1A. The connector is used to connect a long wire with the pump connector, and we will simply insert the pump into that connector; therefore, would we need ESD protection for that?

    Would that insertion only be during initial assembly in an ESD controlled environment, or would the end user be connecting/disconnecting the pump?  If it's only in a controlled environment then no protection should be needed.  

    Dharmesh Joshi said:
    Well, we sometimes need an odd load switch in our design, but to keep our BOM list to a minimum and cost done, I was thinking that I could simply use the DRV8231A and keep one input forced to GND. 

    Yeah absolutely, that would work.  

    Dharmesh Joshi said:
    We aim to use the SOIC version, but with the exception of connecting the GND pad to copper pours, how can we work out the heat dissipation and how long can we run a motor continuously?

    Unfortunately we don't have any good thermal simulation for these parts, the best we have is the 9.3 Current Capability and Thermal Performance section in the datasheet.  Check that out and run the numbers and it should get you a ballpark.  Beyond that, you can order an EVM and test it out.  Looks like we only have a DRV8251AEVM, so you would have to order that and order DRV8231A devices and swap out the chip on the EVM.  If you aren't already see if you can join the TI Sample program to be able to order free samples of devices and EVMs - Ordering FAQs | TI.com 

    Best,

    Jacob