Current to voltage converter

current to voltage converter

Hi all,
I want to monitor the following current in and out of a battery and to display it on a LM3915 dot/bar display. Basically I need to convert +- 5A to voltage. In others words -minus5Amps = 0Volts, zeroAmp=1Volt, Plus5A=2Volts. The "centre" voltage corresponding to 0 amps is 1 volts. See the schematic below. Any ideas? Thanks.

current to voltage amplifier ad620

The best way to monitor this current is with an instrumentation amplifier. The one that we commonly use is the AD620 made by Analog Devices. This part has a gain selection resistor that allows you to control the current to voltage transfer ratio. It also has a reference pin that allow you to offset the output voltage.
It requires a bipolar power supply, but the rails do not have to be equal. We often use +12V and -5V rails as these are common in our systems. The part requires a good bit of headroom, so do not make the power rails too close to the max output value.
You can also follow the AD620 with a second gain stage of just a regular OPAMP. In this stage you could bump up the amplification some more and produce the output offset you want.