MAX1455 Diagnostic Clip Boost Circuit

Abstract: The MAX1455 high-performance low-cost signal conditioner includes output clipping capability, which is very important diagnostic tool in the automotive applications. This feature can detect various failure mode of the transducer module, including the failed sensors. When a resistive load is applied to the OUT pin during clip, the clip voltage is pulled away from the nominal set point. A solution is presented that prevents output loading from changing the clip voltage value. This is accomplished by using the on-chip uncommitted op amp as a buffer. The PGA and clip circuit output the full voltage range from clip-low to clip-high and the op amp drives the resistive load. This document also describes a way of customizing the pre-programmed clipping limits.