Microchip | MIC1557YM5-TR

The MIC1557YM5 TR IttyBitty™ CMOS RC timer/oscillator and MIC1555 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 open-collector 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 +2.7 V to +18 V supply voltage. The MIC1555/7 is available in the SOT-23-5 5-lead package, and is rated for –40°C to +85°C ambient temperature range.

Key Features:

• +2.7 V to +18 V operation.
• Low current.
• <1 µA typical shutdown mode (MIC1557).
• 200 µA typical (TRG and THR low) at 3 V supply.
• Timing from microseconds to hours.
• “Zero” leakage trigger and threshold inputs.
• 50% square wave with one Resistor, one Capacitor.
• Threshold input precedence over trigger input.
• <15 output on resistance.
• No output cross-conduction current spikes.
• <0.005%/°C temperature stability.
• <0.055%/V supply stability.
• Small SOT-23-5 surface mount package.

Applications:

• Precision timer.
• Pulse generation.
• Sequential timing.
• Time-delay generation.
• Missing pulse detector.
• Micropower oscillator to 5 MHz.
• Charge-pump driver.
• LED blinker.
• Voltage converter.
• Linear sweep generator.
• Variable frequency and duty cycle oscillator.
• Isolated feedback for power supplies.