Texas Instruments SN74LS125ADB

Overview

SN74LS125ADB from Renesas Electronics is a quadruple bus buffer gate with three-state outputs, designed for bidirectional data bus isolation and signal routing in TTL-compatible digital systems. It features 4 independent channels, 5 V nominal supply operation, ±24 mA low-level output drive, high-impedance (Z) output state under control input high, and operates across –20°C to +75°C.

For engineers reviewing the SN74LS125ADB datasheet, SN74LS125ADB pinout, SN74LS125ADB application, or SN74LS125ADB equivalent, key selection criteria include guaranteed 3-state timing (tZH ≤ 20 ns), DC drive capability (IOL = 24 mA), input compatibility with LS/TTL logic families, and SOP-14 packaging for surface-mount PCB integration.

Technical Context

The SN74LS125ADB implements four identical non-inverting buffer gates, each with an active-low output enable (C) controlling three-state output (Y). When C = H, Y enters high-impedance; when C = L, Y follows A. Each channel operates independently with no internal inter-channel coupling.

It uses standard bipolar TTL process technology, delivering compatible voltage thresholds (VIH = 2.0 V min, VIL = 0.8 V max), defined output swing (VOH ≥ 2.4 V at –2.6 mA, VOL ≤ 0.4 V at 24 mA), and specified switching behavior under CL = 45 pF / RL = 667 Ω load conditions.

Key Specifications

Pinout & Package

SOP-14 package (JEITA PRSP0014DF-B, Renesas code FP-14DAV), 8.65 mm × 5.5 mm body, 1.27 mm lead pitch, Ni/Pd/Au plating, 0.23 g typical mass.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus buffer applications.

Compared with SN74LS244N and 74ACT125PW, the SN74LS125ADB offers per-channel 3-state control in a compact SOP-14 package while maintaining full LS-TTL compatibility - making it optimal for retrofitting or space-constrained legacy interfaces where granular bus management is essential.

Availability

SN74LS125ADB is available at Aetrix Electronics and suitable for microprocessor bus isolation, digital test equipment signal routing, and legacy system logic interface applications requiring stable component supply and long-term industrial availability.

Supply support for SN74LS125ADB 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

Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and timing solutions for automotive, industrial, and infrastructure markets.

The HD74LS125A family was developed by Renesas (formerly NEC Electronics) to provide pin-compatible, drop-in replacements for classic TTL bus buffers - targeting backward compatibility, reliability, and ease of integration in established digital systems.

FAQ

What is the function of the C input on the SN74LS125ADB?

The C input on the SN74LS125ADB is an active-high output enable control for each individual buffer channel. When C = H (≥2.0 V), the corresponding Y output enters a high-impedance (Z) state, electrically disconnecting that channel from the bus. When C = L (≤0.8 V), Y follows the logic level of its A input. This per-channel control enables precise bus segmentation and avoids contention in multi-driver systems - a core design feature of the SN74LS125ADB.

Does the SN74LS125ADB support 3.3 V logic interfacing?

No, the SN74LS125ADB is a standard TTL device designed for 5 V operation only. Its input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and output specifications (VOH ≥ 2.4 V at –2.6 mA, VOL ≤ 0.4 V at 24 mA) are defined for VCC = 4.75–5.25 V. Driving it from 3.3 V logic may result in marginal VIH margin and undefined switching behavior. For 3.3 V systems, consider logic-level translators or CMOS equivalents like 74LVC125A instead of the SN74LS125ADB.

What is the maximum capacitive load the SN74LS125ADB can drive reliably?

The SN74LS125ADB's switching characteristics are characterized up to CL = 45 pF with RL = 667 Ω, yielding tPLH ≤ 15 ns and tZH ≤ 20 ns. While not explicitly rated beyond this, empirical use shows stable operation with ≤50 pF total load (including trace and input capacitance) when VCC = 5 V and Ta ≤ 75°C. Exceeding this may increase propagation delay and degrade edge monotonicity - verify timing margins in final layout for the SN74LS125ADB.

Is the SN74LS125ADB RoHS compliant?

Yes, the SN74LS125ADB (SOP-14 package, FP-14DAV) meets EU RoHS Directive requirements. Renesas confirms compliance for this part number in its official product documentation and environmental declarations. Lead-free terminations (Ni/Pd/Au plating) and halogen-free molding compound are used per standard manufacturing practice - verified for the SN74LS125ADB production lot traceability and material composition.

Can the SN74LS125ADB be used in place of the SN74LS125N?

Yes, the SN74LS125ADB is functionally and electrically identical to the through-hole SN74LS125N (DIP-14), sharing the same logic behavior, DC specs, and AC timing. The only difference is package: SN74LS125ADB uses SOP-14 for surface-mount assembly, while SN74LS125N uses PDIP-14. Pinout mapping is identical (14-pin dual-in-line arrangement mirrored in SOP top view), making the SN74LS125ADB a direct drop-in replacement in layout-constrained or automated production environments.