Simple circuits sort out the highest voltage

摘要

In a water-cooled power converter, analog -output sensors measure the cooling water temperature at three locations. If any of the three temperatures rises above a preset threshold, an alarm sounds and attracts the attention of the system's operator. When the alarm activates, knowing which measurement site has reached the highest temperature saves troubleshooting time and prevents system damage. The circuit in Figure 1 delivers an analog-output voltage equal to the highest of three input voltages that drives a display for continuous temperature monitoring. LED indicators identify which of three sensors shows the highest temperature. An external adjustable-threshold comparator (not shown) monitors the analog-voltage output and activates an audible alarm.