OP-AMP Maximum ratings

[kaykan]

Hello,

I have a question about OP-AMP maximum ratings,

Pick an LM358, that have  a maximum voltage of 32V on (VCC - VEE) and 32V on (V+ - V-), now supposing this configuration:



Now if I apply 20V as input I know that the result will be 3.3V, but the OP-AMP will be damaged?

Is a good Idea use an op-amp to protect (for example) an ADC with a configuration like this?

If I apply 40V (over 32V) the op-amp will be damaged?

thanks for help!

.c

[han]

if there is a internal clamp diode, i'm sure it's bye bye for the opamp..

[poorchava]

Refer to the datasheet to get input voltage range. It will usually be expressed as VDD+x if there are clamping diodes or as an absolute value of there are none.

What you are trying to do is not good anyway. I mean you shouldn't drive an ADC with 0...32V signal. Divide it down with a high-impedance divider (several meg, so that source resistance does not affect the measurement too much), then buffer with an opamp that has low bias current and high input impedance (i'd try MCP6051) and use that to drive the ADC.

[kaykan]

Thank you for support!

in the LM385 the maximum ratings is 0V to 32V for VCC, and 0V to 32V for V+/V-, so I suppose that if I set VCC to 3.3V and V+ to 30V the op-amp will not damaged, otherwise I expected a limit for V+/V- to (for example) VCC + 0,5V, right?.

Really thanks for help!