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. These devices are similar in function to the industry standard "555", without a frequency control (FC) pin or an open-collector discharge (D) pin. The threshold pin (THR) has precedence over the trigger (TRG) input, ensuring that the BiCMOS output is off when TRG is high. The MIC1555 can 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.