The SMM150 is a highly accurate power supply voltage supervisor and environmental monitor with provisions for voltage margining of the monitored supply. The part includes an internal voltage reference to accurately monitor and margin the supply to within 1%. The SMM150 has the capability to margin over a wide range from 0.3V to VDD using the internal reference and can read the value of the supply over the I2C bus using an on-chip 10-bit ADC. The monitor and margin levels are set using the I2C serial bus. The SMM150 initiates margining via the I2C bus or by using the MUP or MDN inputs. Once the pre-programmed margin target voltage is reached, the SMM150 holds the converter at this voltage until receiving an I2C command or de-asserting the margin input pin. When the SMM150 is not margining, the TRIM output pin is held in a high impedance state allowing the converter to operate at its nominal set point. Two general purpose input pins are provided for sensing under or overvoltage conditions. A programmable glitch filter associated with these inputs allows the user to ignore spurious noise signals. A FAULT# pin is asserted once either input set point is exceeded.