DESCRIPTION

The MIC1555 IttyBitty® CMOS RC timer/oscillator and MIC1557 IttyBitty® CMOS RC oscillator are designed to provide rail-to-rail pulses for precise time delay or frequency generation.The devices are similar in function to the industry standard "555", without a frequency control (FC) pin or an opencollector discharge (D) pin. The threshold pin (TH) has precedence over the trigger (TR) input, ensuring that the BiCMOS output is off when TR is high.The MIC1555 may be used as an astable (oscillator) or monostable (one-shot) with separate threshold and trigger inputs. In the one-shot mode, the output pulse width is precisely controlled by an external resistor and a capacitor.Time delays may be accurately controlled from microseconds to hours. In the oscillator mode, the output is used to provide precise feedback, with a minimum of one resistor and one capacitor producing a 50% duty cycle square wave.The MIC1557 is designed for astable (oscillator) operation only, with a chip select/reset (CS) input for low power shutdown. One resistor and one capacitor provide a 50% duty cycle square wave. Other duty-cycle ratios may be produced using two diodes and two resistors. The MIC1555/7 is powered from a +2.7V to +18V supply voltage.The MIC1555/7 is available in the SOT-23-5 5-pin package, and is rated for -40°C to +85°C ambient temperature range.