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DRV8212: Parallel Half-Bridge Configurtion

Keith Keller
Expert 7050 points
Part Number: DRV8212
Other Parts Discussed in Thread: DRV8244-Q1

Hello,

The DRV8212 datasheet indicates that the IC can be used to get 8-Amp(peak) in parallel half-bridge.

We are not seeing anything in the data sheet that shows how that control interface mode is configured.

Table 8.3.2.3 discusses it somewhat, but do not see how to specifically configure it.

Could you share any more documentation?    Thanks very much for your help, Keith

  • 0
    TI__Mastermind 23361 points

    Hey Keith,

    See Figure 9-11. Half-bridge mode used as a low-side driver with outputs paralleled.  "By tying the INx pins together and OUTx pins together, as shown in Figure 9-10 and Figure 9-11, the device can drive a single load with half of the RDS(on). This can accommodate larger current requirements. This configuration is called "parallel half-bridge mode.""

    Simply connect the load to GND or VM on one side, and to both OUT1 and OUT2 on the other side.  Leave the MODE pin disconnected/floating.  Also connect IN1 and IN2 to each other (paralleled) so they get the same signal.  Figure 9-19 and Figure 9-20 show examples of driving a motor using high-side and low-side driving when the OUTx pins are paralleled together to create a single half bridge.

    Cheers,

    Jacob

  • 0 in reply to Jacob Thompson
    TI__Expert 7050 points

    Hello,

    So how would I sense motor current by using the high side configuration or low side configurations  in 9-10/9-11?

    Is GND the bridge and logic ground?

    Figure 9-27 shows a current sense amp, but the MODE pin is grounded instead of floating for the parallel half bridge mode.

     Also does the (RDSon) go from 280mohms to 140mohms?

    Thanks very much!  Keith

  • 0 in reply to Keith Keller
    TI__Mastermind 23361 points

    Hey Keith, 

    Keith Keller said:
    So how would I sense motor current by using the high side configuration or low side configurations  in 9-10/9-11?

    I believe a similar way as shown in the datasheet, with a RC filter and a sense resistor, though they might need to be on the device VM instead of GND for certain configuration.  

    Keith Keller said:
    Is GND the bridge and logic ground?

    Yes

    Keith Keller said:
    Figure 9-27 shows a current sense amp, but the MODE pin is grounded instead of floating for the parallel half bridge mode.

    It looks like Figure 9-27 is showing the current sense amp with the DRV8212 set up for bidirectional control of one motor, like in 6.2 Single Motor Operation of the EVM user guide.  

    Keith Keller said:
    Also does the (RDSon) go from 280mohms to 140mohms?

    Yes, it does.  

    FYI, you can test the parallel mode by following these steps in the EVM user guide:

  • 0
    TI__Expert 7050 points

    Hello,

    It seems like you can’t drive a DC brush motor in a forward and reverse direction in the parallel half bridge configuration (8Apeak) due to the IN1 and IN2 are the same PWM output.

    Is that correct?

    Thank you, Keith

  • 0 in reply to Keith Keller
    TI__Mastermind 23361 points

    Hey Keith,

    Correct, but it is because with one side of the motor tied to VM or GND and the other side to OUT1+OUT2, you no longer have a full-bridge for bidirectional control.  It is only half-bridge control, either as high-side or low-side driver.  Hence only needing 1 PWM input signal for 0-100%, but only one direction.  

    Cheers,

    Jacob

  • 0 in reply to Jacob Thompson
    TI__Expert 7050 points

    Hi Jacob,

    Would you have an alternative solution we could use that provides both forward and reverse?

    Thank you, Keith

  • 0 in reply to Keith Keller
    TI__Mastermind 23361 points

    The DRV8243-Q1 looks like the best replacement - it supports 12 Amps peak current bidirectionally, supports the same control modes (1/2-bridge, PH/EN, PWM) and has a relatively small package size of 3x4.5mm. 

    A similar option would be the DRV8244-Q1 with 21 Amps peak current. DRV8256 is another good option supporting 8 Amps with Smart Tune tech.  

    Cheers,

    Jacob