Micropower, Single Supply, Rail-to-Rail Input-Output Instrumentation Amplifiers

The EL8171 and EL8172 are micropower instrumentation amplifiers optimized for single supply operation over the +2. 4V to +5. 5V range. Inputs and outputs can operate rail-to-rail. As with all instrumentation amplifiers, a pair of inputs provide very high common-mode rejection and are completely independent from a pair of feedback terminals. The feedback terminals allow zero input to be translated to any output offset, including ground. A feedback divider controls the overall gain of the amplifier. The EL8172 is compensated for a gain of 100 or more, and the EL8171 is compensated for a gain of 10 or more. The EL8171 and EL8172 have PMOS input devices that provide sub-nA input bias currents. The amplifiers can be operated from one lithium cell or two Ni-Cd batteries. The EL8171 and EL8172 input range goes from below ground to slightly above positive rail. The output stage swings completely to ground (ground sensing) or positive supply - no pull-up or pull-down resistors are needed.