Microchip Technology MIC1555YM5-TR

Overview

MIC1555YM5-TR from Microchip Technology is a CMOS RC timer/oscillator IC designed for precision monostable (one-shot) and astable operation, featuring separate trigger (TRG) and threshold (THR) inputs, 2.7V to 18V supply range, <0.005%/°C temperature stability, and 50% square wave generation with one resistor and one capacitor. It serves in micropower timing circuits such as missing-pulse detection and LED blinkers.

For engineers reviewing the MIC1555YM5-TR datasheet, MIC1555YM5-TR pinout, MIC1555YM5-TR application, or MIC1555YM5-TR equivalent, key selection considerations include its SOT-23-5 package, rail-to-rail CMOS output, dominance of THR over TRG, sub-1μA shutdown capability (when used with CS-enabled variants), and ±2% timing accuracy across microseconds to hours.

Technical Context

The MIC1555YM5-TR implements a BiCMOS RS flip-flop architecture with independent comparator-based TRG (active-low ≤⅓VS) and THR (active-high ≥⅔VS) inputs, where THR takes precedence to ensure deterministic output state transitions. Its internal resistive divider sets precise ⅓VS and ⅔VS reference thresholds without external components.

It supports both monostable (pulse width = 1.1·R·C) and astable (f ≈ 0.7/(R·C) below 1 MHz) configurations using external R-C networks. Output is a totem-pole CMOS driver with <15Ω on-resistance and rail-to-rail swing, enabling direct interface with logic-level MOSFETs or capacitive loads up to 10 pF.

Key Specifications

Pinout & Package

Package: 5-pin SOT-23 (M5), 2.9 mm × 1.6 mm × 1.1 mm body, surface-mount, lead-free and RoHS compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RC timer/oscillator applications.

Compared with NE555DR, MIC1555YM5-TR delivers 99% lower quiescent current and ±2% timing accuracy versus ±5%, but lacks high-current drive. Versus MIC1555YD5-TR, it shares all functionality but uses the standard SOT-23-5 footprint-ideal for designs prioritizing manufacturability over miniaturization.

Availability

MIC1555YM5-TR is available at Aetrix Electronics and suitable for precision timer, LED blinker, time-delay generation, and micropower oscillator applications requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for MIC1555YM5-TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology Inc. is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and timing solutions, with ISO/TS-16949:2009 certification for design and wafer fabrication.

The MIC1555/57 IttyBitty RC Timer/Oscillator product line was engineered for ultra-low-power, high-accuracy timing in space- and energy-constrained systems-replacing legacy bipolar 555 timers with CMOS efficiency and precision.

FAQ

What is the maximum operating frequency of MIC1555YM5-TR in astable mode?

The MIC1555YM5-TR achieves up to 5 MHz in astable configuration with RT = 1 kΩ and CT = 47 pF at VS = 8V. At lower frequencies (<1 MHz), timing follows f ≈ 0.7/(R·C); above 1 MHz, propagation delay dominates, requiring empirical tuning. The MIC1555YM5-TR does not include chip select, so continuous oscillation is inherent-unlike MIC1557 variants with CS shutdown.

Does MIC1555YM5-TR support monostable operation with AC-coupled trigger inputs?

Yes, MIC1555YM5-TR supports falling-edge and rising-edge triggered monostable operation using AC coupling. A series capacitor and pull-up resistor (RC time constant < pulse width) prevent multiple triggering. A diode across the timing resistor enables fast reset. This configuration is documented in Figures 5-5 and 5-6 of DS20005730B, and the MIC1555YM5-TR's zero-leakage inputs ensure stable timing regardless of source impedance.

Can MIC1555YM5-TR generate a 50% duty cycle square wave without additional components?

Yes, MIC1555YM5-TR generates a precise 50% duty cycle square wave using only one resistor and one capacitor in astable mode-by connecting TRG to THR externally. This eliminates the need for diodes or dual resistors required by legacy 555 timers. The MIC1555YM5-TR's matched comparator thresholds (⅓VS and ⅔VS) and rail-to-rail output ensure symmetry; timing accuracy remains ±2% across voltage and temperature.

What is the output drive capability of MIC1555YM5-TR?

MIC1555YM5-TR provides a CMOS totem-pole output with <15Ω on-resistance, delivering 20 mA sink/source at 5V with <0.5 V drop. At 15V, it sustains 20 mA with <1.25 V drop. This allows direct driving of LEDs, small relays, logic inputs, or logic-level MOSFET gates-no buffer stage needed. The MIC1555YM5-TR output exhibits no cross-conduction current spikes, ensuring clean transitions into capacitive loads.

How does MIC1555YM5-TR differ from MIC1557 variants?

MIC1555YM5-TR supports both monostable and astable modes with separate TRG and THR pins, while MIC1557 variants (e.g., MIC1557YM5-TR) are astable-only with combined T/T input and integrated chip select (CS). MIC1555YM5-TR lacks CS, so it cannot enter sub-1μA shutdown-making it ideal for always-on timing. Both share identical supply range, accuracy, and package options, but MIC1555YM5-TR offers greater functional flexibility for one-shot applications.