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ESD321: ESD Circuit

Shuji Ishiwata
Mastermind 6695 points
Part Number: ESD321
Other Parts Discussed in Thread: ESD122, , STRIKE

Tool/software:

Hi All,


I have some questions about ESD321 and ESD122.

(1) The ESD321 has one diode circuit. The ESD122 has two diode circuits.
　　What are the advantages and disadvantages of having one diode circuit and having two diode circuits?

(2) Is the ESD321 effective against negative ESD? If so, please explain how it works.

(3) Is there a graph for the ESD321 that is the same as Figure 4. –8-kV IEC 61000-4-2 Waveform, IO Pin to GND in the ESD122 datasheet?


　　In the ESD321 datasheet, it says Figure 6-4. 8-kV IEC 61000-4-2 Clamping Voltage Waveform, GND to I/O Pin.


Best Regards,
Ishiwata

  • 0
    TI__Expert 5130 points

    Hi Ishiwata, 

    Please see answers below:

    1) The difference between ESD321 and ESD122 is channel count. ESD321 has 1 channel, meaning it can protect 1 line. ESD122 is a 2-channel device and can protect 2 lines. 

    2) ESD321 is effective against negative ESD strikes. ESD321 is a unidirectional device, so it supports voltages from 0 to 3.6V. When a negative strike occurs, ESD321 will clamp almost immediately. For ESD122, since it is a bidirectional device, if a negative strike occurs then it wont clamp until about -8V. 

    3) Since ESD321, is a unidirectional device, the only possibility for a negative strike is from GND to IO. 

    Please let me know if you have any additional questions. 

    Best,

    McKenzie

  • 0 in reply to McKenzie Eaker
    Mastermind 6695 points

    Hi McKenzie,


    Thank you for your answer.

    Regarding (1)
    Since ESD122 can protect with 2 lines, does it have stronger protection than ESD321?
    I am concerned that one-circuit products may be weak against negative ESD.
    Please tell me the advantages and disadvantages of having one diode circuit and having two diode circuits.


    Best Regards,
    Ishiwata

  • +1 in reply to Shuji Ishiwata
    TI__Expert 5130 points

    Hi Ishiwata, 

    I wouldn't say there is necessarily an advantage or disadvantage to having one diode circuit or two diode circuit. It is very dependent on your system and application needs. 

    For example, if you are protecting 4 Ethernet lines (TX+, TX-, RX+, RX-) then you can either use 2- ESD122 devices or 4- ESD321 devices. Sometimes space can be an issue or cost or both, so it depends on what you are looking for.

    Best,

    McKenzie