The LTC®2935 ultra-low power voltage monitor provides system initialization, power-fail warning and reset gen- eration functions. Low quiescent current (500nA typical) makes the LTC2935 an ideal choice for battery-operated applications. Three binary threshold-select inputs confi gure one of eight integrated reset thresholds, available from 3.3V to 2.25V in 150mV increments. Early warning of an impending low voltage condition is provided at the power-fail output (PFO), whose threshold is 150mV above the confi gured reset threshold. Supervisory circuits monitor VCC and pull RST low when VCC drops below the confi gured reset threshold. When VCC is rising from an under-threshold condition, an internal reset timer is started after exceed- ing the reset threshold by 5%. A 200ms reset timeout delays the return of the RST output to a high state. A pushbutton switch connected to the MR input is typically used to force a manual reset. Outputs RST and PFO are available with open-drain (LTC2935-1) or active pull-up (LTC2935-2) circuits. Operating temperature range is from –40ºC to 85ºC.