MP227A

The MP227A has the following features including Built-in 3-pole Filtering;Built-in Oscillator/Driver;High Common Mode Rejection 170 dB;Excellent linearity 0.0075%.

The Analogic MP227A is a precision isolation amplifier that provides an unparalleled combination of linearity, stability, isolation, and very low cost.  It  is  designed  primarily  to replace relays and filter elements in multichannel  data  acquisition systems.  However,  its  unique features make it attractive wherever low-level,  low  frequency  signals must be amplified in the presence of severe common mode interference.The  MP227A  includes  an  internal power oscillator and isolated supply so that no external drivers are needed.  The  isolated  power(4V nominal) can be used for open ther-mocouple  indication  or  offsetting strain gauge inputs.The MP227A was designed as an economically competitive and functionally superior alternative to the relay multiplexing circuits traditionally used in multichannel data acquisition systems. In a typical thermocouple system,the MP227A replaces two functional blocks for each channel-the input filter and a dual relay, as well as the common channel high gain amplifier-and permits high-level, solidstate multiplexing to be used for low cost and high reliability.

The  MP227A  provides  significantly  better isolation and common-mode rejection than low-level relays and it puts the gain at a point in the system where the bandwidth is lowest(prior to multiplexing), thereby reducing total system noise. Even where multiplexing is not used,  the  unusual  combination  of  performance and price makes the MP227A attractive  for  a  wide  variety  of  industrial applications.When many MP227A's are used in a system,a high speed, high level analog multiplexer switches the MP227A outputs to a common analog output bus for subsequent AID conversion.  Any  high  precision  isolation amplifierlfilter used in such a configuration has an  inherent error source of sizable magnitude that is often overlooked, ignored or simply unknown, that is, dumped charge effects. This Application Note discusses the problem, the solution, and the fringe benefits.