Texas Instruments SN7405DR

Overview

SN7405DR from Texas Instruments is a hex inverter with open-collector outputs, designed for wired-OR and wire-AND logic implementation in 5-V TTL systems. It features six independent inverters, 16-mA low-level output current capability, 0.2–0.4 V typical VOL at IOL = 16 mA, and operates across 0°C to 70°C. It is used in bus interface, level translation, and active-low signal combining applications.

For engineers reviewing the SN7405DR datasheet, SN7405DR pinout, SN7405DR application, or SN7405DR equivalent, key selection considerations include its open-collector architecture requiring external pull-up resistors, compatibility with legacy TTL logic families, and SOIC-14 packaging for space-constrained PCB layouts.

Technical Context

The SN7405DR implements six identical inverting buffers with open-collector NPN output transistors, enabling direct connection to shared bus lines without contention. Its input structure matches standard TTL thresholds (VIL = 0.8 V, VIH = 2 V), ensuring interoperability with 74xx-series logic.

Each inverter delivers up to 16 mA sink current at VCC = 5 V, with propagation delays of tPLH = 40–55 ns and tPHL = 8–15 ns under RL = 4 kΩ/400 Ω and CL = 15 pF conditions. The device draws ICCL = 18–33 mA at VI = 4.5 V and ICCH = 6–12 mA at VI = 0 V.

Key Specifications

Pinout & Package

SN7405DR is housed in a 14-pin SOIC (D) package, 3.90 mm wide, 8.65 mm long, and 1.75 mm maximum height, with 1.27 mm pitch and gull-wing leads. Pin 1 is marked by a beveled corner or dot; the device is lead-free (NIPDAU) and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar hex inverter applications.

Compared with SN74LS05DR and SN74S05DR, the SN7405DR occupies the middle ground: faster than LS but less power-hungry than S, making it optimal for general-purpose TTL interfacing where balanced speed, drive, and power are needed.

Availability

SN7405DR is available at Aetrix Electronics and suitable for industrial bus interface, LED driver interface, level translation interface, and legacy system glue logic requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN7405DR 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 with over 90 years of analog and logic IC innovation, delivering high-reliability components for industrial, automotive, and communications markets.

The SN7405DR belongs to TI's legacy 74xx TTL logic family, engineered for robust interoperability, predictable timing, and field-proven reliability in fixed-function digital systems.

FAQ

What is the function of SN7405DR?

The SN7405DR is a hex inverter with open-collector outputs. Each of its six channels inverts the input signal and drives an open-collector output that must be pulled up externally. This architecture enables wired-OR logic, level translation, and direct interface to higher-voltage loads. The SN7405DR operates strictly as a logic inverter-not a buffer, latch, or driver with push-pull outputs.

Does SN7405DR require external pull-up resistors?

Yes, SN7405DR requires external pull-up resistors on all six outputs (pins 2, 4, 6, 8, 10, 12) because it uses open-collector NPN transistors. Without pull-ups, outputs remain floating in the high state and cannot assert a valid logic HIGH. Typical values range from 1 kΩ (for speed) to 10 kΩ (for low power), selected based on load capacitance and rise-time requirements.

Can SN7405DR be used with 3.3-V logic inputs?

No, SN7405DR is not guaranteed to operate correctly with 3.3-V logic inputs. Its input thresholds are specified for TTL (VIH = 2.0 V min, VIL = 0.8 V max), and while a 3.3-V HIGH may register, noise margin is reduced and DC parameters (e.g., IIH, IIL) are not characterized below 4.75 V VCC. For 3.3-V systems, use a proper level translator or 3.3-V-compatible logic family instead of SN7405DR.

What is the maximum sink current per output of SN7405DR?

The SN7405DR supports a maximum sink current of 16 mA per output (IOL) under recommended operating conditions (VCC = 4.75–5.25 V, TA = 0–70°C). This rating is validated at VOL ≤ 0.4 V. Exceeding 16 mA risks violating the output low-voltage spec or degrading long-term reliability. Total device supply current (ICCL) reaches up to 33 mA when all inputs are HIGH.

Is SN7405DR pin-compatible with SN7405N?

Yes, SN7405DR is functionally and pin-compatible with SN7405N. Both share identical logic functionality, pin numbering (1A–6A, 1Y–6Y, GND, VCC), and electrical specifications. The only difference is package: SN7405N uses 14-pin PDIP, while SN7405DR uses 14-pin SOIC (D). Layout adaptation is required, but no schematic or logic redesign is needed when migrating from SN7405N to SN7405DR.