LM556CMX Equivalent & Substitute Parts

Part Overview

The LM556CMX is a dual timer/oscillator IC based on the 555 timer architecture, designed for clock and timing applications with a maximum frequency of 100kHz. Manufactured by Texas Instruments, this component is packaged in a 14-SOIC surface mount configuration and operates across a 4.5V to 16V supply voltage range.

The LM556CMX is classified as obsolete, which necessitates identifying functionally equivalent substitute components for new designs or production continuity. The primary substitute identified maintains functional compatibility while offering improved availability and compliance status.

Substiute Parts

LM556CMX

Texas InstrumentsIn Stock: 4239LM556CMX Datasheet

Current PartRFQ

NE556DR

Texas InstrumentsIn Stock: 48114NE556DR Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the LM556CMX is determined by the following critical parameters:

• Functional Type: 555 Type, Timer/Oscillator (Dual) architecture
• Package Compatibility: 14-SOIC surface mount package with identical pin configuration
• Electrical Specifications: Supply voltage range 4.5V ~ 16V, maximum frequency 100kHz
• Operating Temperature Range: 0°C ~ 70°C
• Pin Count and Pitch: 14 pins with 0.154" (3.90mm) width

The NE556DR meets all substitution criteria, maintaining identical functional architecture, package form factor, and electrical operating parameters. Both components are manufactured by Texas Instruments and share the same base product number designation (556 series).

Parameter Comparison

Engineering Selection Recommendations

The NE556DR is the direct functional equivalent for the obsolete LM556CMX. Selection should be based on the following factors:

Product Availability: The LM556CMX is obsolete with limited remaining inventory. The NE556DR is actively manufactured by Texas Instruments with substantial stock availability, ensuring supply chain continuity.

Regulatory Compliance: The NE556DR meets ROHS3 compliance requirements, whereas the LM556CMX is non-compliant. For applications subject to RoHS directives or customer compliance requirements, the NE556DR is the appropriate selection.

Electrical Performance: Both components operate within identical voltage and temperature ranges. The NE556DR specifies a maximum supply current of 20 mA compared to 10 mA for the LM556CMX. This difference reflects typical manufacturing variations in the 555 timer architecture and does not affect functional compatibility in standard timing applications.

Pin Compatibility: Both components utilize the 14-SOIC package with identical pinout, enabling direct PCB-level substitution without layout modifications.

Frequently Asked Questions (FAQ)

Q: Can the NE556DR be used as a direct replacement for the LM556CMX on existing PCBs?

A: Yes. Both components share identical 14-SOIC pinout, supply voltage range (4.5V ~ 16V), operating temperature range (0°C ~ 70°C), and 555 timer architecture. No PCB modifications are required for substitution.

Q: What is the significance of the higher supply current specification for the NE556DR?

A: The NE556DR specifies 20 mA maximum supply current versus 10 mA for the LM556CMX. This represents typical manufacturing variation in the 555 timer family and does not indicate functional differences. Both values are within standard 555 timer specifications and do not affect circuit operation in typical timing applications.

Q: Why is the LM556CMX classified as obsolete?

A: The LM556CMX has been discontinued by Texas Instruments. The NE556DR represents the current active production equivalent within the 556 dual timer family.

Q: Are there compliance differences between these components?

A: Yes. The NE556DR is ROHS3 compliant, while the LM556CMX is RoHS non-compliant. For applications requiring RoHS compliance, the NE556DR is the appropriate selection.

Q: Is the 14-SOIC package the only available form factor for the NE556DR?

A: The NE556DR is available in Tape & Reel (TR) packaging for automated assembly. The 14-SOIC package configuration remains consistent across packaging options.

Q: Can the NE556DR be used in designs originally specified for the LM556CMX without circuit redesign?

A: Yes. Functional equivalence and identical electrical parameters enable direct substitution without circuit modifications. Standard design verification practices should be applied to confirm performance in the specific application context.