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OPA855: ESD protection diode

Amelie Zheng
Genius 10865 points

Part Number: OPA855

Hi Team,

The figure is a schematic diagram of the 855 ESD protection diode. The two in the box are on the die. So is the arrow pointed to by the die also?

Why add one more diode(the arrow pointed) between In+ and -?

Add one more question. Could you provide 855 the iv curve of positive and negative input terminal and the iv curve of the ESD diode on the power supply rail be provided?

  • 0
    Guru 48395 points

    The drawing is showing 3 pairs of ESD steering diodes on the V+, V- and FB pins to the supplies - these are important for handling mainly, not when the part is in the board - unless you anticipate driving beyond the supplies for some reason. these diodes steer an ESD event to the absorption device across the supplies. 

    The two back to back diodes across the inputs are  for in situ overdrive protection while the part is operating - if you drive it so hard that a voltage build up across the inputs, while the amplifier is overdriven, these will protect the input stage from damage. 

    None of these operate normally - but they do add capacitance to these pins. 

  • 0
    Guru 140200 points

    Hi Amelie,

    Amelie Zheng said:
    Why add one more diode(the arrow pointed) between In+ and -?

    Look carefullly, the arrowed diode isn't between IN+ and IN- :-)

    Kai

  • 0
    TI__Mastermind 32435 points

    Hello Amelie, 

       For the second question, we can take this conversation offline. 

    Thank you,

    Sima