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AFE4490: Diode required at Input and Output?

Dennis Ryu
Prodigy 80 points
Part Number: AFE4490

The AFE4490EVM has diodes placed at the input and output terminals:

But if we were to use the AF4490 in Common-Anode mode (instead of H-Bridge), would these diodes D1, D2, D3, and D4 still be required?

Would their purpose be for noise reduction or something else instead of enabling the H-Bridge?

Thank you.

  • 0
    Prodigy 80 points

    If the diodes D1, D2, D3, and D4 are not required, would it be ok to directly connect our LED and PD to the nets colored in Blue?

  • 0 in reply to Dennis Ryu
    TI__Mastermind 19815 points

    Hi,

    I will try to get back to you around 4/5.

    Thanks

  • 0 in reply to ChienChun Yang
    TI__Mastermind 19815 points

    Hi,

    Here are some comments after talking to the team.

    1. Those diodes are for ESD protection diodes.

    ---------------------------------------------------

    2. Customer have options and will need to test whether to

    a. remove the ESD protection diodes ONLY IF customers doesn't care about the ESD protection.

    or

    IF customers care about ESD protection,

    b. keep the same ESD protection diodes ONLY IF customers doesn't care about the LEDs driving performance

    or

    c. change to other ESD protection diodes if customers want to test whether other ESD protection diodes could be better than the original one(i.e. b)

    ---------------------------------

    Reasons for above b,c options are

    1. the original ESD protection diodes are old and after checking its datasheet(https://www.diodes.com/assets/Datasheets/BAV99W.pdf), it has higher leakage current and parasitic capacitance, which could affect the LEDs driving performance.

    2. my team may suggest put/replace ESD protection diodes similar to this one https://www.ti.com/lit/ds/symlink/tpd1e01b04.pdf?ts=1680622503058&ref_url=https%253A%252F%252Fwww.google.com%252F

    , which has much lower parasitic capacitance(around 0.2pF) and lower leakage current(< 10nA).

    ----------------------------------------------

    It’s suggested to start testing&comparison&doing data collection&analysis early to know&compare how much the ESD protection diodes could or could not affect the LEDs usages IF customers care about ESD protection.

    --------------------------

    3. Yes, customer may connect the PD and LED they want to do tests.

    Thanks