LM556CM - Dual 555 Timer | Fairchild | Industrial
MPN: LM556CM ✓ ActiveLM556CM Overview
A 555-type timer is a programmable timing IC that can operate as an astable oscillator or a monostable pulse generator. In astable mode, external resistors and a capacitor establish repetitive switching, while the output produces a continuous waveform. In monostable mode, a trigger starts one timed output pulse. The LM556CM places two such timer functions in a single 14-SOIC package, making it useful where PCB area is constrained.
The principal verified specifications include a 4.5 V to 16 V supply range, operation up to 3 MHz, and TTL-compatible normally on and normally off outputs. The dual architecture allows both timer sections to be used together or independently. Its 14-SOIC package is a surface-mount package compatible with conventional automated PCB assembly, although exact board dimensions and pin mapping must be confirmed against the selected manufacturer datasheet before layout.
The LM556CM combines two classic 555-type timing blocks with separate timing and output functions. Its operating range supports conventional 5 V and 12 V system rails, while the stated upper limit of 16 V provides additional design headroom. The 3 MHz maximum operating frequency identifies it as a general-purpose timing solution rather than a precision real-time-clock or low-frequency timer.
Typical uses include industrial pulse generation, retriggerable delay circuits, dual-tone generation, LED flashers, motor or solenoid timing, test equipment, and general control systems. Two timers in one package can simplify designs that need independent delays, complementary pulse outputs, or two adjustable waveforms while reducing the number of external IC footprints.
Circuit design should account for timing-component tolerances, supply decoupling, output loading, and the required trigger and reset levels. Because the verified data identifies the package and core ratings but does not provide a complete pin map or detailed output-current limits, engineers should verify those details in the manufacturer datasheet for the exact branded source being procured.
This page consolidates verified distributor data, source links, package information, drop-in sourcing alternatives, and practical selection guidance. It is designed to support faster engineering comparison while clearly identifying specifications that require confirmation from the exact manufacturer datasheet.
Drop-in alternatives for LM556CM — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
LM556CM
✅ Drop-InContact for price
View Datasheet →LM556CM
✅ Drop-InContact for price
View Datasheet →LM556CM
✅ Drop-InContact for price
View Datasheet →NE556DT
✅ Drop-In📋 Reference alternative (not in catalog)
LM556CM Specifications
| Device Type | 555 Type, Timer/Oscillator (Dual) IC |
| Number of Timer Sections | 2 sections |
| Operating Modes | Astable and monostable |
| Supply Voltage Range | 4.5 V to 16 V |
| Maximum Operating Frequency | 3 MHz |
| Output Compatibility | TTL compatible |
| Normally On Output | Available |
| Normally Off Output | Available |
| Package | 14-SOIC |
| Package Pin Count | 14 pins |
| Mounting Type | Surface mount |
LM556CM 14 pins Pin Configuration Guide
Pin configuration for LM556CM (14 pins package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for LM556CM.
Refer to the datasheet for full pin configuration.
Typical Applications
LM556CM is suitable for 6 applications: Industrial Pulse Generator, Dual-Tone and Waveform Generator, Retriggerable Delay and Sequencing, LED Flash and Indicator Driver, Motor and Solenoid Timing Control, Test and Measurement Timing.
Industrial Pulse Generator
The LM556CM fits industrial pulse-generation circuits because it combines two 555-type timer sections in one 14-SOIC package and operates from 4.5 V to 16 V. One section can establish the pulse repetition rate while the other controls pulse width, reducing the number of timing IC footprints on a control board. Its verified 3 MHz upper operating frequency provides margin above ordinary low-frequency process timing needs. The implementation should use separate trigger and reset paths, observe the exact manufacturer pinout, and select resistor and capacitor values from the applicable datasheet because timing tolerances are not included in the supplied data.
Recommended
Dual-Tone and Waveform Generator
The LM556CM is suitable for dual-tone or multi-waveform generation because its two timer/oscillator sections can operate independently within one 14-SOIC package. The verified 4.5 V to 16 V supply range supports 5 V and 12 V control systems, while operation up to 3 MHz provides capability above basic low-speed flashing circuits. Each timer can be configured using external timing networks, subject to the selected datasheet. Board designers should compare the two outputs with timing tolerances, minimize loop area around timing components, and confirm TTL-compatible output behavior against downstream logic requirements.
Recommended
Retriggerable Delay and Sequencing
The LM556CM can implement retriggerable delay and sequencing functions because it provides two monostable-capable timer sections in a single package. One section may generate a delayed response while the other manages a second stage or complementary interval, and the TTL-compatible normally on and normally off outputs can support coordinated downstream logic. Its 4.5 V minimum operating voltage is compatible with common 5 V industrial control systems. Verify trigger pulse width, reset behavior, output delay, and minimum pulse duration in the exact manufacturer datasheet before relying on the device for safety-related timing.
Recommended
LED Flash and Indicator Driver
The LM556CM is applicable to LED flash, blink, and indicator patterns because two independent astable timer sections can produce repetitive or offset output waveforms in one 14-SOIC package. The normally on and normally off TTL-compatible outputs provide convenient logic signals for external transistor or indicator-driver stages, while the 4.5 V to 16 V range supports conventional control rails. The timer IC should not automatically be assumed to drive LED current directly because the verified output-current limit is unavailable. Check output sourcing and sinking specifications, use an appropriate transistor or driver where needed, and account for resistor tolerance when setting flash duration.
Recommended
Motor and Solenoid Timing Control
The LM556CM can support motor, solenoid, and actuator timing in control systems by using one timer for a command delay and the second for an interlock or pulse-duration interval. The 14-SOIC package consolidates two timing functions, while the verified 4.5 V to 16 V operating range suits 5 V and 12 V embedded control environments. Its outputs are TTL-compatible, making them suitable for interfacing with suitable logic or driver stages. Because output-current and temperature-limit details were not supplied, do not connect a load directly without checking the exact datasheet, and add suitable flyback protection for inductive loads.
Recommended
Test and Measurement Timing
The LM556CM is useful in test and measurement equipment for generating stimulus clocks, setting delayed switching windows, or producing complementary timing signals. Two timer sections in one 14-SOIC package reduce board area, while the verified 3 MHz capability is appropriate for instrumentation timing above very-low-frequency flashing rates. The TTL-compatible normally on and normally off outputs can coordinate compatible digital logic, although the actual output drive and rise or fall times must be checked in the exact manufacturer datasheet. Use short timing-component routes, stable supply decoupling, and calibrated reference components when timing accuracy matters.
Recommended
Recommended Products Summary
Engineering reference data for LM556CM — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LM556CM | LM556CM | LM556CM | NE556DT |
|---|---|---|---|---|---|
| Brand | Fairchild Semiconductor | Texas Instruments | onsemi | STMicroelectronics | Texas Instruments |
| Package | 14-SOIC | 14-SOIC | 14-SOIC | 14-SOIC | 14-SOIC |
| Device Type | 555 Type, Timer/Oscillator (Dual) IC | 555 Type, Timer/Oscillator (Dual) IC | 555 Type, Timer/Oscillator (Dual) IC | 555 Type, Timer/Oscillator (Dual) IC | 14-pin dual 555 timer |
Key Differentiators
- Dual timer sections consolidate two timing functions (vs NE556DT)
- Verified operation up to 3 MHz (vs NE556DT)
- TTL-compatible dual normally on and normally off outputs (vs LM556CM)
Design Notes
Do not assume that every LM556CM listing is electrically identical solely because the MPN is the same. The verified search results associate the designation with Fairchild Semiconductor, Texas Instruments, and onsemi, and comparison data also identifies STMicroelectronics. Before schematic release, compare the exact manufacturer datasheet for supply current, trigger and reset thresholds, output drive, timing tolerance, temperature range, and package pinout. Keep the manufacturer and package suffix visible in the BOM to avoid an unintended substitution during procurement.
Place each timer section's timing resistors and capacitor close to the associated device pins, and keep the timing-loop return path short to minimize switching transients and false triggering. Add normal supply decoupling near the IC, but use the exact manufacturer recommendation for capacitor value and ESR because the supplied data does not include those requirements. Route trigger and reset signals away from high-current switching nodes and provide a defined state for unused inputs according to the selected datasheet.
Design the 4.5 V to 16 V supply interface so that transients and ringing cannot exceed the maximum operating voltage. The LM556CM is a timer rather than a power regulator, so its input must be supplied by a suitably regulated rail. Verify output sourcing and sinking capability before driving TTL inputs, LEDs, relays, or other loads. Where the load exceeds the verified information available for this page, use an appropriate transistor or logic buffer and account for its propagation delay in time-sensitive sequences.
Timing accuracy depends on the actual resistor and capacitor tolerances and on device-specific temperature behavior. Generic 555 timing equations may not cover every LM556CM source, so calculate the network from the selected manufacturer datasheet and include worst-case tolerances. If two sections interact through common supply or ground paths, verify that current transients from one timing network do not shift the other section's trigger point. A dedicated local ground return can reduce timing jitter.
Compliance Information
The supplied verified web results did not provide explicit RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals statements for the target. Compliance must be confirmed using the datasheet and declarations for the exact manufacturer source being purchased.
