Texas Instruments SN75477DR

Overview

SN75477DR from Texas Instruments is a dual NAND peripheral driver IC designed for high-voltage, high-current switching in electromechanical interface circuits. It delivers 300 mA continuous output current per channel, supports 100 V typical output breakdown voltage, features diode-clamped TTL/MOS-compatible inputs, and operates across 0°C to 70°C - commonly used in relay drivers, solenoid controls, and printer hammer-driver systems.

For engineers reviewing the SN75477DR datasheet, SN75477DR pinout, SN75477DR application, or SN75477DR equivalent, key selection criteria include its dual-NAND logic function, 5 V nominal supply compatibility, output clamp diode protection (70 V, 300 mA), and SOIC-8 package suitability for industrial control PCBs with space-constrained layouts.

Technical Context

The SN75477DR implements two independent NAND gate drivers with pnp transistor inputs that reduce input current draw and enable direct interfacing with TTL or MOS logic. Each channel integrates high-voltage bipolar output transistors rated for 100 V breakdown and includes built-in clamp diodes for inductive transient suppression up to 70 V at 300 mA.

Its logic behavior follows positive-logic NAND: Y = A·S̅ (output low only when A = high and S = low). The device is characterized for operation at 4.5 V–5.5 V supply, exhibits propagation delays of 200–350 ns, and avoids latch-up even after conducting 300 mA into 55 V inductive loads.

Key Specifications

Pinout & Package

SN75477DR is housed in an 8-pin SOIC (D) package with 1.27 mm lead pitch, 3.9 mm body width, and 1.75 mm max height - optimized for automated assembly and thermal performance in compact control modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-NAND peripheral driver applications.

Compared with SN75477P and ULN2003A, the SN75477DR uniquely combines dual-NAND logic control, per-channel enable, fast switching, and SOIC-8 manufacturability - making it the only option supporting gated, synchronized dual-load actuation in space-constrained SMT designs.

Availability

SN75477DR is available at Aetrix Electronics and suitable for printer mechanisms, industrial relay interfaces, solenoid control systems, and legacy logic translation applications requiring stable component supply and long-lifecycle support.

Supply support for SN75477DR 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 solutions for industrial, automotive, and communications markets.

The SN75477DR belongs to TI's legacy peripheral driver family, engineered specifically for robust, high-voltage electromechanical interface applications in commercial-grade control systems.

FAQ

What logic function does the SN75477DR implement?

The SN75477DR implements two independent NAND gate drivers. Its truth table shows output Y goes low only when input A is high AND enable input S is low (Y = A·S̅). This enables active-low enable control of each channel - a key feature distinguishing it from simple buffer or inverter drivers. The SN75477DR uses pnp transistor inputs to minimize input current while maintaining TTL/MOS compatibility.

Can the SN75477DR drive inductive loads like relays or solenoids directly?

Yes, the SN75477DR is explicitly designed for inductive load driving. Each output includes an integrated clamp diode rated for 70 V reverse voltage and 300 mA forward current, which safely dissipates flyback energy from relays and solenoids. The device is characterized for no latch-up even after conducting 300 mA into 55 V inductive transients - a critical reliability feature confirmed in TI's SLRS025A datasheet.

What is the maximum continuous output current per channel of the SN75477DR?

The SN75477DR is characterized for 300 mA continuous output current per channel under recommended operating conditions (TA ≤ 70°C, VCC = 4.5–5.5 V). Absolute maximum rating allows 400 mA continuous, but sustained operation above 300 mA requires careful thermal design due to power dissipation limits - especially in the SOIC-8 package, which has a θJA of 100°C/W.

Is the SN75477DR compatible with 3.3 V logic inputs?

No, the SN75477DR is not reliably compatible with 3.3 V logic inputs. Its input threshold is defined for TTL: VIH ≥ 2.0 V (min), VIL ≤ 0.8 V (max), and it is specified only for 4.5–5.5 V supply operation. While some 3.3 V CMOS outputs may exceed 2.0 V, marginal noise margins and lack of characterization at 3.3 V make direct interfacing non-recommended. A level shifter or buffer is advised for 3.3 V systems.

What package type and lead finish does the SN75477DR use?

The SN75477DR uses an 8-pin SOIC (D) package with 1.27 mm lead pitch and NIPDAU (nickel-palladium-gold) lead finish. It is RoHS-compliant, MSL Level-1 rated (unlimited floor life), and supplied in large tape-and-reel format (2500 units per reel). The package drawing is TI's D0008A, with body dimensions of 4.9 mm × 3.9 mm × 1.75 mm max height.