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Queastion about input voltage range of the INA101 Inst amp

E

Exador

Jan 1, 1970
0
I'm trying to use an INA101 instrumentation amp with +-12v supply rails.
The data sheet specifies the input voltage range as +-10v min and +-12v typical with
+-15v supplies. My question is how do I figure out what the input range would be with
supply voltages other than +-15v, specifically +-12v? Also curious what would happen
if I get to close to the + supply rail on the + input pin?

Thanks
Mike
 
J

John Popelish

Jan 1, 1970
0
Exador said:
I'm trying to use an INA101 instrumentation amp with +-12v supply rails.
The data sheet specifies the input voltage range as +-10v min and +-12v typical with
+-15v supplies. My question is how do I figure out what the input range would be with
supply voltages other than +-15v, specifically +-12v? Also curious what would happen
if I get to close to the + supply rail on the + input pin?

Thanks
Mike

Most opamps maintain a fairly constant wasted voltage as the supply
changes, so I would expect an input common mode range of only +-7v to
+- 9v for this chip operated from 12 volt supplies.
 
J

John Popelish

Jan 1, 1970
0
Exador said:
Thanks John, I thought that was the case, but was confused by the minimum supply
voltage rating of +-5v. I was able to scale the input down so that it never excedes
6v and some strange behavior disappeared.

This makes sense if there is +-5 volts of supply headroom needed above
the input range. At +-5 volt supply, the useable input range
approaches zero but may still be usable for very low amplitude
signals. Chips operating at the minimum possible supply voltage are
seldom very useful.
 
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