A
[email protected]
- Jan 1, 1970
- 0
I'm looking at the schematic, Figure 3 at
http://www.analog.com/UploadedFiles/Application_Notes/58837442106604AN244.pdf
I want to use this for high-side current sensing. I start running into
problems when either op-amp outputs have to fall to near 0. I am using
an op-amp that supposedly works down to 0, but it's not getting close
enough. I'm working with a single polarity supply, and a 0.1 ohm sense
resistor. I am using 10K for R1-R4, and 2.5K for Rg....such that the
output is 10 times the input difference (1 volt per amp).
Now if I could shift the output up 1 volt, such that zero current is 1
volt, 1 amp is 2 volts, etc, that might solve my problem. But I'm
trying to avoid negative voltages. I realize if I tie the grounded end
of R4 to a voltage it will do exactly what I want, but the output of
one op-amp has to drop below 0 for low current measurements.
Any ideas?
http://www.analog.com/UploadedFiles/Application_Notes/58837442106604AN244.pdf
I want to use this for high-side current sensing. I start running into
problems when either op-amp outputs have to fall to near 0. I am using
an op-amp that supposedly works down to 0, but it's not getting close
enough. I'm working with a single polarity supply, and a 0.1 ohm sense
resistor. I am using 10K for R1-R4, and 2.5K for Rg....such that the
output is 10 times the input difference (1 volt per amp).
Now if I could shift the output up 1 volt, such that zero current is 1
volt, 1 amp is 2 volts, etc, that might solve my problem. But I'm
trying to avoid negative voltages. I realize if I tie the grounded end
of R4 to a voltage it will do exactly what I want, but the output of
one op-amp has to drop below 0 for low current measurements.
Any ideas?