NE555/SA555/NA555PRECISION TIMERSPin DescriptionsPin NamePin NumberDescription GND 1 Ground TRIG 2 Trigger set 1/3VCC OUT 3 Timer output RESET 4 Reset active low CONT 5 External adjustment of internal threshold and trigger voltages THRES 6 Threshold set to 2/3 VCC T DISCH 7 Low impedance discharge path VCC 8 Chip supply voltage UCFunctional Block DiagramNEW PRODRESET can override TRIG, which can override THRESHFunctional TableNominal TriggerThresholdDischargePin NameOutputVoltageVoltageSwitch GND Irrelevant Irrelevant Low On TRIG <1/3VCC Irrelevant High Off OUT <1/3VCC <2/3VCC Low On RESET <1/3VCC <2/3VCC As previously established