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TS3A27518E: SD card application, is there a lower capacitance switch

Part Number: TS3A27518E
Other Parts Discussed in Thread: TMUX1574

Hi,

My customer use TS3A27518E for SD card, if run PASSMARK Burn in SD card test item, got 100% fail (can't access SD card) with UHS-I (SDR104 ) card

We wonder it might be caused by the total load capacitance over Spec. which is 40pF for the Max. value( host – PCB trace – switch – ESD diode –SD card slot –SD card )
For TS3A27518E switch’s load capacitance is around 21.5pF, is there a lower load capacitance switch solution can replace TS3A27518E?

Or you have any suggestion for the issue?

Attached is schematic.SD.pdf

  • Hello,

    Thank you for sharing the schematic. 

    TS3A27518E is TI's only switch in this configuration. I can suggest a multiple chip solution with lower Con, if you are interested.

    Can you explain more what the PASSMARK test and 100% fail results indicate? What additional troubleshooting steps have you tried? Have you confirmed the control inputs of the switch are correct?

    Thanks,
    Kate

  • Hi Dickson,

    My customer would like to know multiple chip solution with lower Con, could you please propose a solution ?

  • Hi Jim,

    The TMUX1574 is a 4ch, 2:1 device with a low CON specification - Typical - 7.5pF, Max - 12pF. Since the customer needs 6ch, 2:1 device, we will have to use 2x,TMUX1574 in the design which will be 8ch, 2:1 and leave two channels unused.

    The TMUX1574 device has additional features - 2Ghz Bandwidth, 1.8V logic compatible, Fail-safe logic (control pins can powerup before the supply) and Powered-off protection upto 3.6V.

    Please note that the TMUX1574 is a newer device with better features and 2x will still be cost/size effective solution. They can either use the small uQFN package RSV (2.6mm x 1.8mm) or the SOT-23-THIN leaded package (4.3 mm x 3.36mm)

    I have attached example pin mapping for 2x TMUX1574 to the customer use case. Please make sure the customer uses datasheet for final schematic for logic and specification purposes.

    Let us know if any further questions.

    TMUX1574_Usage.xlsx