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OPA2227: Input bias current

Part Number: OPA2227

Hello, 

I am using the OPA2227 as a voltage follower to buffer a reference voltage in my circuit. Reading the datasheet, I noticed that it is specified that when using OPA2227 as  an unity gain buffer, the input current has to be limited to 20mA. Why is that, concerning that the input bias current is limited to 10nA on the datasheet? Does this concern some transient behaviour, or are high input currents common in real voltage followers?

  • user5252845,

    You are confusing OPA2227 two completely different specifications; the maximum IB of +/-10nA refers to the input bias current under normal (linear) operation where user has no control over its magnitide (just like IQ).  On the other hand, 20mA max input current refers to the Absolute Maximum Ratings input current that user must control when taking the input above or below the rail (non-linear operation) and by doing so forward bias one of the ESD protection diodes located between the input terminal and the supply rails; under such condition, user must limit the maximum input current to 20mA, typically by adding a series input resistor, or risk damaging ESD input protection diode.