The LTC2935 ultra-low power voltage monitor provides system initialization, power-fail warning and reset generation functions. Low quiescent current (500nA typical) makes the LTC2935 an ideal choice for battery-operated applications.Three binary threshold-select inputs configure one of eight integrated reset thresholds, ranging from 1.6V to 3.45V in pre-determined increments. Early warning of an impending low voltage condition is provided at the powerfail output (PFO), whose threshold is above the configured reset threshold. Supervisory circuits monitor VCCand pull RST low when VCCdrops below the configured reset threshold. When VCCis rising from an under-threshold condition, an internal reset timer is started after exceeding 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/LTC2935-3) or active pull-up (LTC2935-2/LTC2935-4) circuits. Operating temperature range is from –40°C to 85°C.ApplicationsPortable EquipmentBattery-Powered EquipmentSecurity SystemsPoint-of-Sale DevicesWireless Systems