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AFE4403: Benefits between H-bridge mode VS Push-Pull mode

David__
Genius 3585 points
Part Number: AFE4403
Other Parts Discussed in Thread: CC3220SF-LAUNCHXL,

Hello, I'm David. I use CC3220SF-LAUNCHXL and a custom AFE4403 module that uses the SPH7050.

I don't see more information when I choose the H-bridge mode or the Push-Pull common anode mode. The following question is created, maybe due to my lack of electrical engineering knowledge.

I believe there will be pros and cons to make the user to choose the configuration.

Are there any benefits when I use the H-bridge configuration, such as

- lower LED power consumption

- faster LED turn on time

- get better readings from LED2-ALED2VAL, LED1-ALED1VAL

?

  • 0
    TI__Genius 12555 points
    Hi David,

    Choice of H-bridge or Push-Pull depends on the optical sensor module you have.

    Regards,
    Prabin
  • 0 in reply to Prabin Yadav
    Genius 3585 points

    Hi, Prabin.

    1. You mean if the AFE4403 module I have has a circuit configuration as the "Figure 52" (LED_DRV_SUP is connected to the external supply)
    I should always configure the CONTROL2 register (Bit 11 TXBRGMOD) to 0 (LED driver is configured as an H-bridge), right?

    2. After I finish prototyping the firmware with this custom module, I will create a custom PCB that will populate AFE4403, SPH7050, and TI's MCU on my custom PCB.
    In this case, I can choose whether to connect the circuit like "Figure 52" or "Figure 53".

    Before choosing the circuit connection and PCB prototyping, I wish to ask for your recommendation.
    When creating my custom AFE4403 PCB, is the H-bridge connection better for
    - lower LED power consumption
    - faster LED turn on time
    - get better readings from LED2-ALED2VAL, LED1-ALED1VAL
    ?

    I hoped to search benefits when using the H-bridge connection for the AFE4403 in the datasheet. However, I couldn't find it, so I'm asking this here.

  • 0 in reply to David__
    TI__Genius 12555 points
    Hi David,

    I would rather say, if your LEDs aren't connected back to back then you have option to connect them to the AFE in pull pull mode. In this option you can leave the supply to LED_DRV_SUP pin.
    However if you LEDs are connected in a back to back fashion, you have to use H Bridge mode and have to connect an external power source to the LED_DRV_SUP pin.

    There is no difference between the H bridge and the push pull mode with respect to power consumption, switching or LED on time.
    Only restriction I see is from the configuration of the LEDs in the optical module.

    Regards,
    Prabin.
  • 0 in reply to Prabin Yadav
    Genius 3585 points

    Thanks, Prabin.

    Prabin Yadav said:
    if you LEDs are connected in a back to back fashion

    Just to clarify, does the "Back to Back" mean the connection described in the purple block?

    Prabin Yadav said:
    Only restriction I see is from the configuration of the LEDs in the optical module.

    Aha, since there are other LED modules besides SPH7050, you mean that the AFE44 series was trying to provide more option to choose regarding the LED module?

    After double checking your meanings, I will close this thread. Thanks for your answer.

  • 0 in reply to David__
    TI__Genius 12555 points
    Hi David,

    Your understanding of the back to back connection is correct.
    Yes, AFE4403 gives you option to connect both types of optical module.

    Regards,
    Prabin