TSV632 - negative input current allowed?

christian · ‎2013-06-27

Posted on June 27, 2013 at 11:53

Hello,

the datasheet for the OpAmp TSV632 allows a maximum input current of 10mA (page 4).

There's no sign given, so I suppose negative input currents aren't allowed.. But I'm not sure and it would help me, if they would be allowed..

So, could someone clarify this, please?

I have series resistors in front of the inputs which would limit the input current to -0.6mA in the worst case.. But I also noticed the input voltage dropping under the allowed Vcc- -0,2V, so it looks for me as current limiting is not enough and I also have to limit the voltage..

Thanks in advance,

Christian

#amplifier-input-protection

Anthony BOIMOND · ‎2013-06-28

Posted on June 28, 2013 at 17:32

Hello Christian,

In fact, both negative and positive currents are allowed in the input pins.

In case current is forced ''into'' or ''out of'' the amplifier input pins, then what happens is that this current will flow through the ESD protection diodes.

The ESD protection diodes are meant to protect the input pins against voltage surges positive or negative. For each one of the amplifier input pins, one diode is connected between VCC- and IN (cathode in IN), the second diode between VCC+ and IN (cathode in VCC+).

In your test conditions, you force a negative current (therefore out of IN pin) and this current comes from the ESD diode connected to VCC-. As long as you maintain the current below 10mA, you don't have to worry about the ''VCC- - 0.2V'' specification: the ''0.2V'' should be read as the typical forward voltage of the ESD diode, it can be greater value.

Hope this can help,

Best regards.

Anthony

christian · ‎2013-07-04

Posted on July 04, 2013 at 11:35

Hello Anthony,

thanks for this inside information. That's great news and really made my day.

Best regards,

Christian