Texas Instruments CD74AC238M96G4

Overview

CD74AC238M96G4 from Texas Instruments is a 3-line to 8-line decoder/demultiplexer IC designed for high-speed memory decoding and data-routing systems. It features three enable inputs (G1 active-high, G2A/G2B active-low), ±24mA output drive, 1.5V–5.5V supply operation, and propagation delays as low as 3.8ns at 5V - enabling use in fast address decoding for SRAM, ROM, and FPGA configuration interfaces.

For engineers reviewing the CD74AC238M96G4 datasheet, CD74AC238M96G4 pinout, CD74AC238M96G4 application, or CD74AC238M96G4 equivalent, this device supports cascaded 24- and 32-line decoding without external inverters, delivers balanced tPLH/tPHL timing, and meets MIL-STD-883 ESD requirements (±2kV HBM), making it suitable for industrial control, test equipment, and embedded logic subsystems requiring deterministic decode latency.

Technical Context

The CD74AC238M96G4 implements a standard 3-to-8 binary decoder with three independent enable controls that allow hierarchical expansion and demultiplexing functionality. Its CMOS architecture ensures SCR-latchup resistance and rail-to-rail input compatibility across 1.5V–5.5V VCC.

Propagation delays are tightly balanced between all eight outputs and across input types: select inputs (A/B/C) exhibit 3.8–15ns delay at 5V, while strobe inputs (G1, G2A/G2B) show faster response (3.0–11.9ns), supporting priority-based enable sequencing in multi-chip decode trees.

Key Specifications

Pinout & Package

CD74AC238M96G4 is supplied in a 16-pin SOIC (D) package measuring 9.9 mm × 6.0 mm, with gull-wing leads and industry-standard footprint. The thermal pad is absent - thermal management relies on PCB copper area connected to GND via standard SOIC land pattern.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 decoder/demultiplexer applications.

Compared with SN74AC138N and CD74HC238E, CD74AC238M96G4 offers superior extended-temperature operation (–55°C to +125°C), tighter propagation delay matching, and verified ±2kV HBM ESD protection - making it the preferred choice for mission-critical industrial and automotive decode functions where reliability and timing determinism are non-negotiable.

Availability

CD74AC238M96G4 is available at Aetrix Electronics and suitable for industrial control systems, test equipment signal routing, and FPGA configuration logic requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74AC238M96G4 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 specializing in analog, embedded processing, and logic solutions with over 50 years of innovation in high-reliability logic ICs.

The CD74AC238M96G4 belongs to TI's AC-series advanced CMOS logic family, engineered specifically for high-speed memory decoding and data-routing applications demanding low power, rail-to-rail voltage operation, and robust latchup immunity.

FAQ

What is the maximum operating frequency supported by the CD74AC238M96G4?

The CD74AC238M96G4 does not specify a maximum clock frequency directly, but its propagation delay (tPD) determines usable edge rate. At 5V, tPD is 3.8–15 ns, supporting reliable operation up to approximately 67 MHz for decode-enable timing windows. System-level frequency depends on setup/hold margins of connected devices - always verify timing closure with worst-case tPLH/tPHL values from Section 4.8 of the CD74AC238M96G4 datasheet.

Can the CD74AC238M96G4 be used as a demultiplexer, and how is that configured?

Yes, the CD74AC238M96G4 can operate as a 1-to-8 demultiplexer. Tie the data signal to one of the three enable inputs - typically G1 (active-high) - while applying address bits to A, B, and C. When G1 = HIGH and G2A = G2B = LOW, the data appears inverted on the selected Yx output (active-low). This configuration is explicitly validated in TI's Application Information section and supports clean signal routing in test and measurement systems.

Does the CD74AC238M96G4 require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs of the CD74AC238M96G4 must be externally held at VCC or GND. Floating CMOS inputs cause increased ICC, unpredictable output states, and potential device malfunction. TI recommends tying unused A/B/C or enable pins directly to VCC or GND using short PCB traces; do not rely on internal leakage or PCB parasitics. This requirement is documented in Section 4.3 and Application Report SCBA004.

What is the thermal performance of the CD74AC238M96G4 in its SOIC (D) package?

The CD74AC238M96G4 in SOIC-16 (D package) has a junction-to-ambient thermal resistance (RθJA) of 106.6°C/W, per TI's Thermal Information table. Under typical conditions (25°C ambient, 5V supply, 10% output toggle rate), power dissipation remains below 5 mW - resulting in negligible junction temperature rise (<1°C). No heatsink is required, but ensure ≥1 cm² of 1-oz copper connected to Pin 8 (GND) for optimal thermal stability.

Is the CD74AC238M96G4 pin-compatible with older CD74HC238 or SN74LS238 devices?

No - the CD74AC238M96G4 is not pin-compatible with CD74HC238 (same pinout but different DC specs and timing) or SN74LS238 (TTL logic, different enable polarity and drive strength). While all three share the 16-pin SOIC footprint, the CD74AC238M96G4 uses active-high G1 and active-low G2A/G2B enables, whereas SN74LS238 uses three active-low enables. Swapping requires schematic and layout revision.