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LM258A: ESD Cell protection of AMP input # LM258/ TS321

Part Number: LM258A
Other Parts Discussed in Thread: TS321, , LM324A, LM258

Dear sir,

Customer wants to check whether there are ESD cell protection from Positive input (IN+) / Negative Input (IN-)  to the power supply (V+/V-) inside?

AMP list:   



If not, 

Q1:   how to explain LM258A/TS321 can pass the HBM/CDM ESD test?

Q2:   If the input voltage of LM258A/TS321 is over the power supply,  usually we add one resistor in serial to limit the current less than 10mA.  and now no ESD cell at IN+/IN- to VCC & GND,  how to do the over-voltage protection?  Just add external diodes to GND/VCC?



  • These devices have no diodes from the inputs to the positive supply. (This is why the input voltage is allowed to be higher, even without a series resistor.) But there are diodes from the negative supply to the inputs.

    ESD protection is done with the equivalent of a Zener diode.

  • Jack,

    An ESD cells are made of normal transistors that are optimized for ESD protection and give no other functional benefit. Therefore it is no surprise that normal transistors that are functional parts of the amplifier will also have some inherent ESD protection value.

    TS321 and LM324A do not have ESD specific cells. The "B" variants do have ESD cells. For all LM258 and TS321, the characteristics of the input is diode like conduction to V- pin and no conduction to V+ pin. Positive input voltage greater than maximum supply voltage is not acceptable. Try to limit negative current to 1mA and send positive overvoltage to ground unless sending it to V+ (VCC)  would always reduce that voltage to a safe level.