Appendix D - Bridge Circuits
A bridge circuit generally outputs a small differential voltage. The LJTick-InAmp provides the amplification needed to acquire such a signal, converts the differential signal to single-ended, and provides a 2.5 volt reference voltage (VREF) that can be used for excitation.
A common example would be a Wheatstone bridge made of 350 ohm strain gauges. If VREF/GND is used to provide the excitation voltage for the bridge, it will draw about 2.5/350 = 7 mA, and the common mode voltage (Vcm) of the differential signal will be about 1.25 volts. The outputs would be connected to IN+ and IN-. If Voffset is set to 1.25 volts and the gain is set to 201, the allowable input range for the LJTIA is –0.00616 to +0.00622 volts (with 0-2.5 volt output).
See our bridge circuit application note for additional relevant information.