Dear All

I want a current to voltage converter, which is capable of converting 700mA current to voltage. From the simulation result in PSPICE, most of the op-amps (LM324, OP07 etc...) only capable of converting between 1mA to 40mA.Once the input current crosses more than 40mA, output is clipped. Which op-amp can handle this much current.

 

Hello,

Take a look at the attached spreadsheet with opamps from National.
Remove the .txt at the end.

Greetings,
Bertus

 

try this:

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1154,C1009,C1077,P10220

or if you want a more discrete solution look at the jpg I attached.

 

Does it matter if there is a shunt resistor involved? Say .1Ω?

 

no shunt resistor cannot be connected, because a high impudence is required on the input of op-amp

 

Opamps are perfectly happy looking into low impedance sources.

The typical way or converting large currents to voltages is to use a shunt resistor, such as the one in Bill Marsden's circuit. The cool feature of Mr. Marsden's circuit is that it changes a voltage referenced to the postive supply to one that is referenced to ground. Maybe all you need is a small resistance, such as 0.1 ohms to ground (to give 70 mv out when you have 700 ma).

If you need to keep the voltage drop to zero, then you are back to finding a high current output opamp, in which case Burtus's spreadsheet should help.

Does that cover it?

 

no shunt resistor cannot be connected, because a high impudence is required on the input of op-amp

Then look at hall-effect sensors or other non-contact current sensors. Your circuit example has a very low input impedance -- 50-ohms.

Bill Marsden's circuit. The cool feature of Mr. Marsden's circuit is that it changes a voltage referenced to the postive supply to one that is referenced to ground.

Which circuit is this?