xx555 Precision Timers1 Features 3 DescriptionThese devices are precision timing circuits capable of1• Timing From Microseconds to Hoursproducing accurate time delays or oscillation. In the• Astable or Monostable Operation time-delay or mono-stable mode of operation, the• Adjustable Duty Cycle timed interval is controlled by a single external• TTL-Compatible Output Can Sink or Source resistor and capacitor network. In the a-stable modeUp to 200 mA of operation, the frequency and duty cycle can becontrolled independently with two external resistors• On Products Compliant to MIL-PRF-38535, and a single external capacitor. All Parameters Are Tested Unless OtherwiseNoted. On All Other Products, Production The threshold and trigger levels normally are twoProcessing Does Not Necessarily thirds and one-third, respectively, of VCC. These Includelevels can be altered by use of the control-voltage Testing of All Parameters. terminal. When the trigger input falls below the triggerlevel, the flip-flop is set, and the output goes high. If 2 Applications the trigger input is above the trigger level and the• Fingerprint Biometrics threshold input is above the threshold level, the flipflop is reset and the output is low. The reset (RESET) • Iris Biometricsinput can override all other inputs and can be used to• RFID Reader initiate a new timing cycle. When RESET goes low,the flip-flop is reset, and the output goes low. Whenthe output is low, a low-impedance path is providedbetween discharge (DISCH) and ground.The output circuit is capable of sinking or sourcingcurrent up to 200 mA. Operation is specified forsupplies of 5 V to 15 V. With a 5-V supply, outputlevels are compatible with TTL inputs