Texas Instruments SN75471D

Overview

SN75471D from Texas Instruments is a dual peripheral AND driver IC designed for high-voltage, high-current switching in industrial and embedded control systems. It delivers 300 mA continuous output current per channel, supports up to 70 V off-state output voltage, operates from 4.75 V to 5.25 V supply, and functions across 0°C to 70°C ambient temperature - enabling direct drive of relays, lamps, and MOSFET gates in logic-buffered interface applications.

For engineers reviewing the SN75471D datasheet, SN75471D pinout, SN75471D application, or SN75471D equivalent, key selection criteria include its TTL-compatible diode-clamped inputs, latch-up immunity at 55 V after conducting 300 mA, medium-speed propagation delays (25–55 ns), low-level output voltage ≤0.7 V at 300 mA load, and SOIC-8 package compatibility with standard PCB assembly processes.

Technical Context

The SN75471D implements two independent AND-gate drivers with open-collector npn output transistors, where each gate's output is internally connected to the base of its respective output transistor. Inputs are TTL-compatible and diode-clamped, enabling robust noise immunity and direct interfacing with 5 V logic families.

Each channel features internal base-drive resistors (1 kΩ, 4 kΩ, 1.6 kΩ) and emitter termination, supporting saturated switching into inductive loads up to 300 mA while maintaining no latch-up at 55 V. The device lacks internal clamping diodes across outputs but relies on external flyback protection for inductive switching.

Key Specifications

Pinout & Package

SN75471D uses an 8-pin SOIC (Small Outline Integrated Circuit) package with 1.27 mm lead pitch and 1.75 mm maximum height, optimized for surface-mount assembly and thermal performance in compact industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual high-voltage AND driver applications.

Compared with SN75471P, the SN75471D offers superior manufacturability in automated SMT lines and smaller PCB footprint, while ULN2003A trades logic integration and voltage margin for built-in inductive load protection and channel count - making each suitable for distinct subsystem roles rather than drop-in substitution.

Availability

SN75471D is available at Aetrix Electronics and suitable for relay control interfaces, lamp drivers, MOSFET gate drivers, and memory bus buffers requiring stable component supply in commercial-temperature industrial electronics.

Supply support for SN75471D 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 U.S.-based semiconductor company specializing in analog, embedded processing, and logic products for industrial, automotive, and communications markets.

The SN75471D belongs to TI's legacy peripheral driver family, engineered for robust 5 V logic interfacing with high-voltage, high-current loads in cost-sensitive industrial control and instrumentation systems.

FAQ

What logic function does the SN75471D implement?

The SN75471D implements two independent AND gates whose outputs drive open-collector NPN transistors. In positive logic, Y = A · B - the output transistor turns ON only when both inputs A and B are high. This behavior is explicitly defined in the SN75471 FUNCTION TABLE and confirmed by the schematic showing base drive tied to the AND gate output. The SN75471D does not perform NAND or OR functions; those are implemented by SN75472D and SN75473D respectively.

Can the SN75471D drive inductive loads like relays safely?

Yes, the SN75471D is characterized for no latch-up at 55 V after conducting 300 mA, making it suitable for relay coil driving. However, it does not include internal flyback diodes - external diodes must be placed across the relay coil to clamp inductive kickback. The 70 V off-state output voltage rating ensures safe blocking during flyback events, provided the external diode limits voltage to within this limit.

What is the maximum continuous current per channel of the SN75471D?

The SN75471D is characterized for 300 mA continuous collector current per channel at 25°C ambient, with derated capability at higher temperatures. At TA = 70°C, the SOIC-8 package supports 464 mW total power dissipation, limiting practical continuous current to approximately 250–280 mA depending on V_CE(sat) and layout thermal resistance. Peak current up to 500 mA is allowed for ≤10 ms pulses at ≤50% duty cycle.

Is the SN75471D pin-compatible with SN75451B or SN75461?

No - although the SN75471D is functionally interchangeable with SN75451B and SN75461 in terms of logic and driver behavior, it is not pin-compatible. The SN75471D uses an 8-pin SOIC or PDIP package with dedicated 1A/1B/1Y/2A/2B/2Y/V_CC/GND pins, whereas SN75451B and SN75461 use different pinouts and package types (e.g., 14-pin DIP). Board redesign is required for substitution.

Does the SN75471D require external pull-up resistors on its outputs?

Yes, the SN75471D features open-collector NPN outputs (1Y and 2Y), which can only sink current. To generate a valid high-level signal or drive a load referenced to a positive rail, external pull-up resistors - or direct connection to a load tied between V_CC (or higher voltage) and the output - are mandatory. The value of the pull-up resistor depends on required rise time, load current, and supply voltage, typically ranging from 1 kΩ to 10 kΩ for 5 V systems.