APX803S/809S/810S MPU Supervisor Circuits Diodes Inc. APX803S/809S/810S MPU Supervisor Circuits are used to monitor power supplies in μP, μC, and digital systems. The APX803S provides excellent circuit reliability and low cost by eliminating external components. The circuits are available with different reset thresholds designed to support different supply voltages (+5V, +3.3V, +3.0V, and +2.5V). These circuits assert a reset signal whenever the VCC supply voltage falls below a preset threshold. This keeps it asserted for at least 240ms after VCC has risen above the reset threshold.