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SE555Q is precision timing circuit capable of producing accurate time delays or oscillation. In the time-delay or monostable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the astable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor. 

The threshold and trigger levels normally are two-thirds and one-third, respectively, of VCC. These levels can be altered by use of the control-voltage terminal. When the trigger input falls below the trigger level, the flip-flop is set, and the output goes high. If the trigger input is above the trigger level and the threshold input is above the threshold level, the flip-flop is reset and the output is low. The reset (RESET) input can override all other inputs and can be used to initiate a new timing cycle. When RESET goes low, the flip-flop is reset, and the output goes low. When the output is low, a low-impedance path is provided between discharge (DISCH) and ground. 

The output circuit is capable of sinking or sourcing current up to 200mA. Operation is specified for supplies of 5V to 15V. With a 5V supply, output levels are compatible with TTL inputs. 


  • Electric Horn


  • Timing from Microseconds to Hours
  • Astable or Monostable Operation
  • Adjustable Duty Cycle
  • TTL Compatible Output Can Source or Sink up to 200mA
  • Automotive Grade
  • "Green" Molding Compound (No Br, Sb)

Product Specifications

Product Parameters

Maximum Frequency (MHz) 0.1
Maximum Output Rise Time 300 ns
Supply Current @ VCC = 5V (Output Low) 3 mA
Supply Current @ VCC = 5V (Output High) 2 mA
VCC Min 4.5 V
VCC Max 15 V
Operating Ambient Temperature Range -40 to 125 °C

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Orderable Part Number Authorized Distributor Quantity Inventory Date Buy Online Region
SE555QS-13 Mouser Electronics Inc. 2108 8/3/2020 Buy Now United States
SE555QS-13 Digi-Key Electronics 4625 8/2/2020 Buy Now United States