Texas Instruments CD4556BMT

Overview

CD4556BMT from Texas Instruments is a dual 1-of-4 decoder/demultiplexer IC in a 16-pin SOIC package, operating across -55°C to +125°C, with supply voltage range 3 V to 18 V, and propagation delay of 120 ns at 5 V. It functions as a logic-level address decoder in industrial control panels requiring discrete channel selection.

For engineers reviewing the CD4556BMT datasheet, CD4556BMT pinout, CD4556BMT application, or CD4556BMT equivalent, this page delivers verified package mapping, validated pin functions, confirmed timing specs, and two field-tested alternative parts for legacy system redesigns and obsolescence mitigation.

Technical Context

The CD4556BMT implements two independent 1-of-4 decoders, each accepting two binary inputs (A0/A1) and enabling active-high outputs (Y0–Y3) when its respective enable input (E1/E2) is high. All inputs are CMOS-compatible with hysteresis for noise immunity.

It uses standard CD4000-series silicon-gate CMOS technology, ensuring low static power consumption (< 1 µA at 5 V), rail-to-rail output swing, and compatibility with TTL, MOS, and other CMOS families via level-shifting design.

Key Specifications

Pinout & Package

CD4556BMT is housed in a 16-pin SOIC (D) package, 7.5 mm wide, 10.3 mm long, 2.1 mm height, with 1.27 mm pitch and RoHS-compliant NiPdAu lead finish. Pin 1 located at top-left corner with notch orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual 1-of-4 decoder applications.

Compared with CD4556BMT, CD4556BM96 offers current production status and RoHS compliance, while MC14556BDR2G extends voltage headroom and output strength - both retain identical decode logic and timing behavior for drop-in validation.

Availability

CD4556BMT is available at Aetrix Electronics and suitable for industrial control, aerospace data acquisition, and medical device subsystems requiring stable component supply despite its obsolete status - we maintain legacy inventory with full traceability.

Supply support for CD4556BMT 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

Texas Instruments is a global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial and automotive qualification.

The CD4556B series belongs to TI's legacy CD4000B CMOS logic family, designed for high-reliability, wide-voltage, extended-temperature digital control in mission-critical systems.

FAQ

Is CD4556BMT pin-compatible with CD4556BE or CD4556BF3A?

Yes, CD4556BMT shares identical pinout and logic functionality with CD4556BE (PDIP-16) and CD4556BF3A (CDIP-16). All three use the same 16-pin dual-in-line footprint pattern - only package type (SOIC vs. PDIP vs. CDIP) and thermal/mechanical properties differ. The CD4556BMT pinout matches the standard CD4556B pin assignment defined in TI's SCHS087D datasheet.

What is the maximum clock frequency supported by CD4556BMT for reliable decoding?

The CD4556BMT does not operate on a clock signal - it is a combinational logic device. Its maximum usable input transition rate is determined by propagation delay: at 5 V, t_PD = 120 ns, supporting address changes up to ~4 MHz for clean setup/hold margins. At 15 V, delay drops to 50 ns, enabling ~10 MHz operation in noise-controlled environments.

Can CD4556BMT drive LEDs directly without current-limiting resistors?

No - CD4556BMT outputs are not current-limited. While it can source/sink ±4.2 mA at 15 V, driving an LED requires an external series resistor to set forward current and prevent damage. For example, with a 2 V red LED and 5 V supply, a 330 Ω resistor limits current to ~9 mA - within CD4556BMT's safe operating range.

Does CD4556BMT support mixed-voltage interfacing, such as 3.3 V MCU inputs driving a 12 V CD4556BMT supply?

Yes - CD4556BMT inputs are CMOS-compatible with V_IL ≤ 0.3×V_DD and V_IH ≥ 0.7×V_DD. A 3.3 V logic high exceeds 0.7×12 V (8.4 V) only if level-shifted. Therefore, direct 3.3 V → 12 V interfacing requires a simple transistor or buffer; however, 3.3 V MCU outputs can safely drive CD4556BMT powered at 5 V without translation.

Why is CD4556BMT marked as Obsolete, and is it still reliable for new designs?

CD4556BMT is obsolete per TI's packaging roadmap due to discontinuation of the SOIC-D tape-and-reel variant (M suffix), not functional obsolescence. The silicon die remains identical to active versions like CD4556BM96. Aetrix Electronics supplies fully tested, traceable CD4556BMT units with full lot documentation - suitable for repair, legacy refresh, and low-volume certified designs where SOIC-D form factor is mandated.