The ADM9240 is a complete system hardware monitor for microprocessor-based systems, providing measurement and limit comparison of up to four power supplies and two processor core voltages, plus temperature, two fan speeds and chassis intrusion. Measured values can be read out via an I2C-compatible serial System Management Bus, and values for limit comparisons can be programmed in over the same serial bus. The high speed successive approximation ADC allows frequent sampling of all analog channels to ensure a fast interrupt response to any out-of-limit measurement.