Operating Opamp only in positive range at Vdd-Vss

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1

I have a Bpw32 photodiode and I wish to amplify the signal I receive from it using an op amp. I found a pretty good opamp board that can be easily modified to meet my requirements at the following link:

I just wanted to apply 5V (at Vdd) and 0V (at Vss) and 0V (at GND). But I was reading that opamps always require a positive and a negative voltage to be applied for Vdd and Vss. But in the datasheet in the link above, it says it can be operated with a single power supply and it has input range for positive supply.

So can the opamp that I chose work from 5V - 0V at Vdd - Vss and also connect Gnd to 0V? How can you tell whether this is okay to do or is this not allowed?

The datasheet also said that the wide supply range is +4.5 V to +36 V. Correct me if I am wrong, but this seems to imply I cannot apply 0 - 5V. If that is the case then I will set Vdd = 10V, Vss = 5V and Gnd = 0V.

Thanks

2

"But I was reading that opamps always require a positive and a negative voltage to be applied for Vdd and Vss."

Where did you read this? This is incorrect.

"Correct me if I am wrong, but this seems to imply I cannot apply 0 - 5V. If that is the case then I will set Vdd = 10V, Vss = 5V and Gnd = 0V."

You are wrong and have been corrected.

Op Amps do not have a Gnd connection, so I do not know what you propose.

Vdd = 10V and Vss = 0V (Gnd?), and depending upon how you are using the Op Amp you may have to generate 5V (a voltage divider may do) for some of your biasing.

Notice that the output will swing +/- 5V about the midpoint of 5V. The input should be centered at 5V and swing up and down from there.

3

vaj4088:
Op Amps do not have a Gnd connection, so I do not know what you propose.

Sorry, I have been going over the basics of an Op Amp so I am a bit unfamiliar.

But on the Op Amp board I choose, it has connections for Vdd, Vss, and Gnd. If I connect Vdd = 10V and Vss = 0V, what do I connect to the Gnd connection on the Op Amp board? Do I just ignore it?

And for setting the input midpoint to be 5V, I will just use a typical voltage divider circuit with 2 resistors in series and I will put the photodiode in between them and send the voltage signal to the op amp.

voltageDiv_Photodiode.PNG

4

That rail-to-rail op-amp will be fine with a single supply of 5V. Connect Vss and GND, apply 5V to Vdd.

You can use a photodiode in photovoltaic mode with a single supply op amp, if you connect it in this simplified way:

But there are caveats, outlined in this presentation: http://edge.rit.edu/edge/P09051/public/photodiodeamplifers.pdf

5

tackymime:
I have a Bpw32 photodiode and I wish to amplify the signal I receive from it using an op amp. I found a pretty good opamp board that can be easily modified to meet my requirements at the following link:

Schmartboard OpAmp

Not really appropriate, that's prewired as a non-inverting voltage gain amp, not a transconductance
amplifier.

A bare rail-to-rail dual opamp in DIP8 is what you probably need.