MIC1557YM5TR - IttyBitty 555 RC Oscillator 5MHz SOT-23-5 | Microchip
MPN: MIC1557YM5TR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.46 | $0.46 |
| 10 | $0.42 | $4.20 |
| 100 | $0.38 | $38.00 |
| 500 | $0.34 | $170.00 |
| 1,000 | $0.3 | $300.00 |
MIC1557YM5TR Overview
A 555-type timer/oscillator is a classic analog building block that generates precise time delays or square-wave frequencies using an external resistor-capacitor (RC) network. Within the power-management and clock-timing hierarchy, it functions as a low-cost oscillator IC, sitting between discrete RC astable circuits and integrated clock generators.
Key features include a wide 2.7V to 18V operating supply range, a 5 MHz maximum oscillation frequency, CMOS technology for low power consumption, and a shutdown pin that reduces quiescent draw to microamp levels. Rail-to-rail output pulses swing the full supply range, making the output directly compatible with both 3.3V and 5V logic when operated from those rails.
The MIC1557 differs from its companion MIC1555 by internally tying the trigger and threshold comparators together, simplifying astable oscillator connections; the MIC1555 retains separate trigger and threshold pins for timer (one-shot) applications. Both devices replace the industry-standard NE555 in space-constrained designs where the 8-pin package is too large.
Typical applications include LED flashers and lamp drivers, clock generation for microcontrollers and ADCs, pulse-width and frequency generation, precision time-delay generation, and watchdog or supervisory timing in battery-powered systems.
Design tip: the oscillation frequency is set by one resistor from OUT to the threshold pin and one timing capacitor to ground; keep the timing capacitor dielectric stable (NPO/C0G ceramic) for frequency accuracy.
This page synthesizes verified distributor pricing, drop-in alternative options, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for MIC1557YM5TR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MIC1557YM5
✅ Drop-In📋 Reference alternative (not in catalog)
MIC1555YM5
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MIC1555YM5-TR
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MIC1557YM5-TR
✅ Drop-In📋 Reference alternative (not in catalog)
MIC1557YM5TR Specifications
| Function | RC Oscillator (555 type) |
| Product Family | IttyBitty RC Timer/Oscillator |
| Maximum Frequency | 5 MHz |
| Supply Voltage Range | 2.7 V to 18 V |
| Output Type | Rail-to-rail CMOS, square/pulse |
| Shutdown Pin | Yes |
| Technology | CMOS |
| Package | SOT-23-5 |
| Pin Count | 5 |
| Mounting Type | Surface Mount |
| Packing | Tape & Reel (TR) |
| Lead Free | Yes (LEAD FREE per FindIC listing) |
| Comparable Legacy Part | NE555 timer |
MIC1557YM5TR Pin Configuration
| Pin 1 | OUT — Rail-to-rail square-wave oscillator output |
| Pin 2 | T — Tied trigger/threshold node - external RC network connection |
| Pin 3 | GND — Ground reference |
| Pin 4 | SHDN — Shutdown control - halts oscillation and reduces supply current |
| Pin 5 | VDD — Power supply, 2.7V to 18V |
Typical Applications
MIC1557YM5TR is suitable for 6 applications: LED Flasher and Indicator Circuits, Microcontroller Clock Generation, ADC Sampling and Conversion Triggering, Precision Time-Delay Generation, Battery-Powered IoT and Sensor Node Timing, Tone and Pulse-Width Generation.
LED Flasher and Indicator Circuits
The MIC1557YM5TR excels in LED flasher duty because its CMOS construction draws minimal quiescent current while the rail-to-rail output drives an LED through a single series resistor. Oscillation from sub-hertz blink rates to kHz strobe rates is set by one resistor from OUT to the T pin and one capacitor to ground. Operating from 3.3V battery cells or 12V industrial rails (2.7V-18V range), it replaces bipolar 555 flashers with longer battery life. The SHDN pin allows a host controller to gate the flasher off entirely during sleep, and the 5-pin SOT-23-5 fits indicator designs where board area is dominated by the LED itself rather than the timing IC.
Recommended
Microcontroller Clock Generation
Many cost-sensitive microcontroller and peripheral circuits need only a modest, non-precise clock, and the MIC1557YM5TR delivers up to 5 MHz square waves with a two-component RC network - far cheaper than a crystal oscillator module. The rail-to-rail CMOS output interfaces directly with 3.3V or 5V logic inputs when powered from the matching rail. Frequency accuracy is RC-dependent (roughly a few percent), so it suits watchdog clocks, baud-free state machines, and ADC conversion triggers rather than UART timing. Use NPO/C0G capacitors to limit drift over temperature, and keep the RC node trace short to avoid coupling noise into the threshold comparator.
Recommended
ADC Sampling and Conversion Triggering
The MIC1557YM5TR provides a free-running pulse source for triggering successive-approximation and switched-capacitor ADCs, where the 555 heritage gives clean, fast edges at up to 5 MHz. Placing the SHDN pin under MCU control lets a data-acquisition board duty-cycle the converter clock to save power between samples. In designs using TI TLC or MAX-series ADCs, the oscillator supplies the conversion clock while the controller handles the serial interface. Because the output swings rail-to-rail with CMOS drive, clock-line capacitance is charged quickly, preserving ADC aperture timing even at 100 kHz to low-MHz sample rates; the supply should be locally decoupled with 100 nF to keep RC timing stable.
Recommended
Precision Time-Delay Generation
Using the RC network as a timing element, the MIC1557YM5TR generates programmable delays from microseconds to seconds, useful for power-on reset extension, relay timing, and sequenced enable generation in multi-rail boards. One resistor-capacitor pair sets the delay, and the shutdown pin doubles as an external reset that restarts the timing cycle cleanly. Compared with a microcontroller software delay, the RC oscillator keeps running while the MCU is asleep, and compared with a discrete RC-plus-comparator, it adds hysteresis-internal comparators that give crisp, chatter-free output transitions. For delays better than a few percent, select a 1% resistor and C0G capacitor and budget supply-voltage sensitivity into the timing calculation.
Recommended
Battery-Powered IoT and Sensor Node Timing
In battery-operated IoT nodes, the MIC1557YM5TR acts as a periodic wake-up source: the SHDN pin keeps standby current in the microamp range while an RC-selected interval gates sensor reads or radio wake-ups. Its 2.7V minimum supply aligns with a single lithium cell or two alkaline cells, and its tolerance to 18V means the same BOM serves 12V battery plants in industrial sensor installations. Because the part oscillates reliably at low currents, designers avoid the brown-out behavior bipolar 555s exhibit at low voltage. The oscillator drives MCU interrupt or enable pins directly with rail-matching logic levels; typical battery-life modeling should include the RC network's DC leakage, so choose film or C0G capacitors over high-K ceramics for long-interval timing.
Recommended
Tone and Pulse-Width Generation
The MIC1557YM5TR generates audible tones and PWM-style pulse trains for alarms, buzzers, and simple actuator drivers. Frequency is programmed from tens of hertz (alarm tones) to hundreds of kilohertz (switching or charge-pump clocks) by the RC ratio, and the CMOS rail-to-rail output can drive a piezo transducer directly or gate a small MOSFET for higher loads. In cost-sensitive alarm products the same IC can serve as both tone generator and, via SHDN, the muting switch, removing a dedicated analog switch. Edges are fast and symmetric across the 2.7V-18V range, so duty cycle stays near 50% for symmetric RC connections; verify audible output SPL with the transducer datasheet since the oscillator only defines frequency, not acoustic power.
Recommended
Recommended Products Summary
Engineering reference data for MIC1557YM5TR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MIC1557YM5 | MIC1555YM5 | MIC1555YM5-TR |
|---|---|---|---|---|
| Package | SOT-23-5 | SOT-23-5 - same | SOT-23-5 - same | SOT-23-5 - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Supply Voltage Range | 2.7 V to 18 V | 2.7 V to 18 V | 2.7 V to 18 V | 2.7 V to 18 V |
| Maximum Frequency | 5 MHz | 5 MHz | 5 MHz | 5 MHz |
| Trigger / Threshold Pins | Tied internally (oscillator) | Tied internally (oscillator) | Separate pins (timer) | Separate pins (timer) |
| Shutdown Pin | Yes | Yes | No | No |
| Primary Mode | Astable oscillator | Astable oscillator | Monostable / astable timer | Monostable / astable timer |
| Packing | Tape & Reel | Tube / tray | Tube / tray | Tape & Reel |
Key Differentiators
- Dedicated shutdown pin for gated operation (vs MIC1555YM5)
- Simplified astable wiring with internally tied trigger/threshold (vs MIC1555YM5-TR)
- 5-pin SOT-23-5 versus 8-pin legacy 555 (vs NE555)
Design Notes
Place the timing resistor and capacitor directly adjacent to the OUT and T pins with short, direct traces. The T node is a high-impedance comparator input; long traces there pick up switching noise and cause frequency jitter or duty-cycle distortion. Use a 100 nF ceramic decoupling capacitor within 2 mm of the VDD pin and route GND returns for the RC network back to pin 3 with a clean ground path. Avoid routing fast digital signals near the T node on two-layer boards.
Do not confuse MIC1557 and MIC1555 footprints: although both are SOT-23-5, the pin functions differ (the MIC1555 brings out separate trigger and threshold pins in place of the tied node, and lacks SHDN), so a board laid out for one will not function correctly with the other without a netlist change. Also remember the MIC1557 is oscillator-only - it cannot implement a one-shot monostable directly. Verify shutdown polarity on the schematic: SHDN must be at the correct logic level for oscillation to start at power-up.
Estimated: frequency accuracy depends on the RC network, not the IC, so budget component tolerance: a 1% resistor plus a 5% X7R capacitor can shift frequency by roughly +/-6% before IC effects, and high-K ceramic capacitance falls 10-30% under DC bias and at low supply voltages. For stable timing near 5 MHz, use C0G/NPO capacitors with a 1% resistor and keep the supply well decoupled; the wide 2.7V-18V range means RC charging current varies with VDD, so frequency should be characterized at the actual operating rail.
Compliance Information
FindIC listing identifies the MIC1557YM5-TR as LEAD FREE. RoHS, REACH, and halogen-free status were not stated in the verified web data and should be confirmed from the Microchip product page or datasheet.
