AMC21C12 Isolated Window Comparator Texas Instruments AMC21C12 Isolated Window Comparator is an isolated window comparator with an open-drain output and an optional latch function. The open-drain output is galvanically isolated from the input circuitry by an isolation barrier, which is highly resistant to magnetic interference. The isolation barrier supports a working voltage of up to 200VRMS or 280VDC and transient overvoltages of up to 570VRMS or 800VDC.