MIC1557

Features:

• +2.7V to +18V operation
• Low current
     <1A typical shutdown mode (MIC1557)
     200A typical (TRG and THR low) at 3V 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


Application

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


Pinout




Specifications

Supply Voltage (V_S) ....................................................+22V
Threshold Voltage (V_THR, V_T/T) ..................................+22V
Trigger Voltage (V_TRG, V_T/T) .......................................+22V
Lead Temperature (soldering 10sec.) ..................... 300°C


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 MIC1555/7 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 of MIC1555/7 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-lead package, and is rated for 40°C to +85°C ambient temperature range.