LM556CM Equivalent & Substitute Parts

Part Overview

The LM556CM is a dual timer/oscillator IC manufactured by Texas Instruments, designed for clock and timing applications. This 555-type device operates across a supply voltage range of 4.5V to 16V with a maximum supply current of 10 mA. The component is housed in a 14-SOIC surface mount package with a width of 3.90mm.

The LM556CM is classified as obsolete, making it necessary to identify functionally equivalent substitute components for new designs and ongoing production requirements. Substitutes must maintain compatibility with the 14-SOIC package format and preserve core timer/oscillator functionality while meeting modern compliance standards.

Substiute Parts

LM556CM

Texas InstrumentsIn Stock: 1646LM556CM Datasheet

Current PartRFQ

TLC556MD

Texas InstrumentsIn Stock: 2027TLC556MD Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the LM556CM is determined by the following critical parameters:

Package Compatibility: The substitute must use the 14-SOIC package format with 0.154" width (3.90mm) to ensure direct pin-for-pin compatibility and PCB layout compatibility without redesign.

Functional Type: The substitute must be a 555-type dual timer/oscillator IC to maintain circuit functionality and pinout equivalence.

Supply Voltage Range: The substitute must operate within or encompass the 4.5V to 16V supply voltage range of the original part. Substitutes with wider voltage ranges (such as 5V to 15V) are acceptable provided they cover the operational envelope of the original design.

Surface Mount Technology: The substitute must use surface mount packaging to match the original mounting method.

Electrical Performance: The substitute must support timer/oscillator operation at frequencies compatible with the application. The LM556CM operates at up to 100 kHz; substitutes with higher frequency capability (such as 2.1 MHz) remain functionally compatible for lower-frequency applications.

The TLC556MD meets all substitution criteria and is identified as the manufacturer-recommended substitute.

Parameter Comparison

Engineering Selection Recommendations

The TLC556MD is the direct substitute for the LM556CM based on the following engineering criteria:

Package Equivalence: Both devices use the 14-SOIC package with identical physical dimensions, enabling direct PCB layout compatibility without modification.

Functional Compatibility: Both are 555-type dual timer/oscillator ICs with identical pinout and functional operation, ensuring circuit-level compatibility.

Supply Voltage Coverage: The TLC556MD supply range of 5V to 15V is contained within the LM556CM range of 4.5V to 16V. Applications operating at 5V to 15V will function identically with the substitute.

Compliance Status: The TLC556MD is ROHS3 compliant, addressing regulatory requirements for new designs and production. The LM556CM is RoHS non-compliant and obsolete, making the TLC556MD the appropriate choice for current manufacturing.

Enhanced Performance: The TLC556MD offers superior specifications including lower supply current (720 µA versus 10 mA), extended operating temperature range (-55°C to 125°C versus 0°C to 70°C), and higher maximum frequency (2.1 MHz versus 100 kHz). These enhancements provide design flexibility without compromising backward compatibility.

Availability: The TLC556MD is classified as Last Time Buy with 2000 units in stock, ensuring supply availability for transition planning.

Frequently Asked Questions (FAQ)

Q: Can the TLC556MD replace the LM556CM in existing designs without PCB modification?

A: Yes. Both devices use the 14-SOIC package with identical pinout and physical dimensions. No PCB layout changes are required for direct substitution.

Q: What is the key difference in supply voltage range between these parts?

A: The LM556CM operates from 4.5V to 16V, while the TLC556MD operates from 5V to 15V. For applications using supply voltages between 5V and 15V, the TLC556MD is fully compatible. Applications requiring operation below 5V or above 15V must retain the LM556CM or identify alternative solutions.

Q: Why does the TLC556MD have lower supply current than the LM556CM?

A: The TLC556MD uses LinCMOS technology, which reduces power consumption to 720 µA compared to the LM556CM's 10 mA. This represents a significant power efficiency improvement while maintaining functional equivalence.

Q: Is the TLC556MD suitable for high-frequency applications?

A: The TLC556MD supports frequencies up to 2.1 MHz, compared to the LM556CM's 100 kHz maximum. Applications requiring operation at frequencies below 100 kHz will function identically with the TLC556MD. Higher-frequency capability does not affect lower-frequency operation.

Q: What is the significance of the RoHS compliance difference?

A: The LM556CM is RoHS non-compliant, while the TLC556MD is ROHS3 compliant. For new designs and production subject to RoHS regulations, the TLC556MD is the required choice. Existing designs using the LM556CM may continue operation, but new procurement should transition to the TLC556MD.

Q: Are there any temperature range considerations for substitution?

A: The TLC556MD operates from -55°C to 125°C, providing a wider temperature range than the LM556CM's 0°C to 70°C. Applications within the LM556CM's original temperature range will function identically with the TLC556MD. Extended temperature operation is available with the substitute if required.

Q: What is the product status of the TLC556MD?

A: The TLC556MD is classified as Last Time Buy, indicating limited future availability. Current inventory of 2000 units supports transition planning. Long-term designs should confirm availability with the manufacturer or identify alternative solutions for future production.