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TMUXHS4612: The issue regarding channel switching

yan yan
Prodigy 10 points
Part Number: TMUXHS4612

Tool/software:

Hello TI Engineer, I have a technical inquiry concerning the control of channel switching for the TMUXHS4612 using the EFM8SB1 microcontroller. According to the TMUXHS4612 datasheet, channel switching between A and B can be achieved by setting the logic levels of the EN, D_AB_SEL, and SIDEBAND_SEL pins. However, when configuring these pins to a high-low-low state, the B channel fails to turn off and the A channel does not activate. Could you please confirm whether additional configuration is required for successful channel switching with the TMUXHS4612? Additionally, I would appreciate any recommended diagnostic methods to identify the cause of this behavior. Thank you for your assistance.

  • 0
    Prodigy 10 points

    In addition to the high-low-low level signal, I have also tried setting eight types of level signals including high-low-high and high-high-low, but none of them could turn off Channel B and turn on Channel A.

  • 0 in reply to yan yan
    TI__Mastermind 18145 points

    Hello Yan Yan,

    According to the schematic you provided the EN pin is pulled down to ground. The TMUXHS4612 is an active high mux. Pulling down the EN disables switching. Try connecting it to a voltage source and check if the issue is resolved.

    Thanks,

    Nir 

  • 0 in reply to Nir Gilgur
    Prodigy 10 points

    Hello Nir Gilgur,
    Thank you for your reply. I have disconnected the EN connected resistor from GND and directly connected EN to the voltage source of the MCU, but the switch still cannot be enabled.
    Thanks,
    yan

  • 0 in reply to yan yan
    TI__Mastermind 18145 points

    Hello Yan Yan,

    Understood, in order for channel B to turn off channel A to be connected D_AB_SEL needs to be low. Are you toggling this pin? Can you share waveforms of the SEL, DAx, DBx, and Dx pins you are trying to switch? 

    According to the schematic the D_AB_SEL is connected to SW_HS_SEL. What is it referenced to? What does HS mean?

    Thanks,

    Nir 

  • 0 in reply to Nir Gilgur
    Prodigy 10 points

    Hello,Nir Gilgur,
    In order to turn off Channel B, I have connected the signals EN, D_AB_SEL, and SIDEBAND_SELl to three pins of the EFM8SB1 chip respectively, and these pins are designated as SW_EN, SW_HS_SEL, and SW_LS_SEL.As for the waveforms of the SEL, DAx, DBx, and Dx pins, I regret that I cannot provide them because I have not yet measured them with an oscilloscope. However, using a multimeter, I have confirmed that the SEL pin is consistently at a low level.

    Thinks,
    Yan

  • 0 in reply to yan yan
    TI__Mastermind 18145 points

    Hello Yan Yan,

    What voltage are you reading at the SEL pins? What if you tie them to ground, does channel B turn off and A turns on?

    Can you try that?

    Thanks,

    Nir 

  • 0 in reply to Nir Gilgur
    Prodigy 10 points

    Hello Nir Gilgur,

    When using the EFM8SB1 to control the TMUXHS4612, the measured voltage at the SEL pin is 0.7V, and Channel B cannot be turned off. When I ground them using a jumper wire, Channel B turns off, but Channel A cannot be turned on.
    Thanks,
    Yan

  • 0 in reply to yan yan
    TI__Mastermind 18145 points

    Hello Yan Yan,

    0.7V on the SEL pin is not low enough to toggle the switch.

    In order to turn off channel B and turn on channel A, you need to have MAX voltage of 0.5V on the SEL pins.
    In order to turn off channel A and turn on channel B, you need to have a MIN voltage of 1.4V on the SEL pins. 

    This is indicated in the datasheet:

    0.7V is between the two values. We don't guarantee operation at that voltage level. More information can be found here. 

    Also, make sure you are following the information from this table below.

    Another reason it is not working is probably D_AB_SEL and SIDEBAND_SEL are not being operated correctly in your application.

    Thanks,

    Nir