The frequency, as well as the duty cycle, are measured by the ST7 timer. The NE555 output is connected to the timer input capture pin. Rev. 1.0 AN1755/0304 1/7. Original: PDF AN1755 NE555 NE555. NE555 AN1755/0304 NE555 cmos CMOS NE555 NE555 APPLICATION OF NE555 NE555 DIAGRAM NE555 astable ntc ne555 NE555 Bipolar timer NE555 timer datasheet: NE555 NE555 Timer Astable Circuit Calculator . NE555 is often mentioned as 555, is a highly reliable electronic device. The 555 timer is capable of being used in astable and monostable circuits. NE555 is an integrated circuit, used in time controllers and clock generators, sometimes used for switching on and off of power supplies too. The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide two or four timing circuits in one package.