• TI Thinks Resolved

TS5A23157: Query regarding Ron resistance and charge injection of analog switch

Part Number: TS5A23157

Hello Sir/Madam,

Hope you are doing well.

This is Akshay Pathak working as a Embedded Hardware Engineer in Teksun Microsys Pvt Ltd.

We evaluated one audio application in which we used "TS5A23157" Analog Switch.

Query :-

  • We need information regarding the parameters about On resistance(Ron) and Charge injection, in this part Ron is 18ohm.
  • So my query is will this much On resistance affect the audio signal and if yes then how much should be the preferable ?
  • As per my understanding Ron 3 to 8 ohm will not affect the audio signal while switching ,so is this correct or not and if not can you guide me through ?
  • Also can you tell us what should be the preferable charge injection so that it won't affect the audio signal.

Thanks & Regards

Akshay Pathak

  • Akshay,

    What type of audio are you switching? Are you switching analog audio centered at 0 V? Are you switching digital audio like I2S or SPDIF?

    Did you like the performance of the TS5A23157 in your evaluation? Are there any issues you are observing that are prompting your questions.

    If your audio signal is centered and you need to pass a negative voltage you will need to use a device like the TS5A2236X family.

    e2e.ti.com/.../421997

    The charge injection is typically not an issue in audio systems because customers mute their systems during the switching.

    Sorry didn't mean to hit the resolved button yet.  (habit)
     
    Thank you,
    Adam

  • In reply to Adam Torma:

    Dear Adam,

    This is Denish Limbachiya working as Embedded Hardware Engineer with Akshay Pathak.

    Nice to E-Meet with you.

    Q: What type of audio are you switching? Are you switching analog audio centered at 0 V? Are you switching digital audio like I2S or SPDIF? 

    A: So basically we want to evaluate basic audio application by using of TI analog switch IC (Part no: TS5A23157) which have an R(ON) resistance 10ohm.In that, we want to disturb the audio signal of headphone speakers as well as a mic. so we implement this analog switch between headphone and mobile.

    So my point is if I use this analog switch (Part no: TS5A23157) IC which have 10 ohm R(ON) resistance. So While switching audio signal in ON  to OFF and again ON  condition so 10ohm R(ON) resistance is effected on an audio signal? As per my knowledge, 3 to 8 ohm R(ON) resistance will not effect on an actual audio signal after switching. So I am correct or not? If I am in wrong way so kindly correct me.

    Kindly let me know if you need more information for it.

    Thanks,

    Denish.

  • In reply to Denish Limbachiya:

    Denish,

    If you are wanting to use a switch for an analog audio application I would recommend the TS5A22362 device because it supports a negative voltage.

    The resistance effect on the audio signal will depend on the speaker load. Typically you want to keep the parasitic resitance on the audio path as small as possible. If you have an 8 ohm switch connected in series with an 8 ohm speaker you will only transfer half the power to the speaker since you created a 50% voltage divider.

    Thank you,
    Adam
  • In reply to Adam Torma:

    Dear Adam,

    Thanks for your valuable inputs, I appreciated it.

    Here I connect the analog switch in series with headphone speakers and mic and they have approx bellow 25ohm impedance. So if I take your suggested part(TS5A22362 ), So what you think 0.79ohm  on resistance is suitable for them in series with <25ohm speakers or mic of headphones. After switching I can get a normal output of switch? i mean after switching there will not distortion arrive in an actual audio signal of headphone?

    Thanks,

    Denish.

  • In reply to Denish Limbachiya:

    Denish,

    The TS5A22362 was specifically designed for analog audio application so its low on-state resistance and low THD make sure the audio signal passes through the switch without issue.

    Thank you,
    Adam