Texas Instruments SN75451BD

Overview

SN75451BD from Texas Instruments is a dual-channel AND-gate peripheral driver IC designed for high-current, high-speed switching in TTL-compatible logic systems. It delivers 300 mA per channel, supports up to 30 V output voltage, features open-collector outputs with diode-clamped TTL inputs, and operates across 0°C to 70°C - commonly used to interface microcontrollers with lamps, LEDs, or relay loads.

For engineers reviewing the SN75451BD datasheet, SN75451BD pinout, SN75451BD application, or SN75451BD equivalent, this page provides verified functional identity, SOIC-8 package mapping, confirmed switching characteristics (tPLH/tPHL ≤ 25 ns), latch-up immunity at 20 V/300 mA, and real-world design context for industrial buffer and power driver selection.

Technical Context

The SN75451BD implements two independent AND-gate logic drivers, each with internally connected TTL-input gates driving NPN output transistors. Its open-collector outputs require external pull-ups and support sink-only operation up to 30 V and 300 mA per channel.

It is characterized for commercial temperature range (0°C to 70°C), uses standard 5 V supply (4.75–5.25 V), and features diode-clamped inputs that simplify interfacing with 3.3 V or 5 V logic without level-shifting - enabling direct connection to MCU GPIOs while maintaining noise immunity and latch-up prevention.

Key Specifications

Pinout & Package

SN75451BD is housed in an 8-pin SOIC (D) package measuring 4.90 mm × 3.90 mm, with standard gull-wing leads and RoHS-compliant NiPdAu plating. Thermal resistance R_θJA = 122.2°C/W enables moderate-power operation without forced cooling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN75451BP and SN75452BD, the SN75451BD offers surface-mount compatibility with optimized thermal performance for automated assembly, while retaining identical electrical behavior to the PDIP variant and differing functionally only from the NAND version - making it the preferred choice for new 5 V TTL-buffer designs requiring AND logic in compact layouts.

Availability

SN75451BD is available at Aetrix Electronics and suitable for industrial HMI panels, LED signage controllers, relay-based power distribution units, and legacy memory interface circuits requiring stable component supply and long-term manufacturability.

Supply support for SN75451BD 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 connectivity solutions, with decades of heritage in logic and interface ICs.

The SN7545xB family was designed to replace legacy SN75450-series drivers with enhanced latch-up immunity and consistent 300 mA drive capability - targeting industrial control, instrumentation, and retro-compatibility applications.

FAQ

What logic function does the SN75451BD implement?

The SN75451BD implements two independent AND gates with open-collector NPN outputs. When both inputs (1A and 1B, or 2A and 2B) are high, the corresponding output (1Y or 2Y) sinks current to ground. This behavior is defined in the device's function table and confirmed in TI's SLRS021E datasheet. The SN75451BD does not provide push-pull or complementary outputs - all outputs require external pull-up resistors.

Can the SN75451BD drive a 24 V relay coil directly?

Yes, the SN75451BD can directly drive a 24 V relay coil as long as the coil current remains ≤300 mA and flyback energy is managed. Its open-collector outputs tolerate up to 30 V off-state voltage, and its latch-up immunity prevents failure during inductive kickback. For reliable operation, use a flyback diode across the coil and ensure the logic supply (VCC) remains within 4.75–5.25 V. The SN75451BD itself does not power the coil - the 24 V is supplied externally via the pull-up.

Is the SN75451BD compatible with 3.3 V microcontrollers?

Yes, the SN75451BD accepts 3.3 V logic inputs reliably due to its diode-clamped TTL inputs. Its V_IL is specified at 0.8 V max and V_IH at 2.0 V min, so a 3.3 V MCU GPIO (typically 0.7×V_DD ≈ 2.3 V high, 0.3×V_DD ≈ 1.0 V low) meets these thresholds. No level shifter is needed, though unused inputs must be tied to VCC or GND to prevent floating states that could cause erratic output behavior in the SN75451BD.

What is the maximum continuous power dissipation for SN75451BD in SOIC-8?

At T_A = 25°C, the SN75451BD in SOIC-8 (D) package has a maximum continuous power dissipation of 725 mW. Above 25°C, it derates linearly at 5.8 mW/°C, resulting in 464 mW at 70°C ambient. This limit assumes proper PCB copper area for heat spreading; actual dissipation depends on load current, duty cycle, and thermal environment. Exceeding this rating risks junction temperature exceeding 150°C, triggering thermal shutdown or permanent damage to the SN75451BD.

Does SN75451BD require external components for basic operation?

Yes, the SN75451BD requires at minimum a 0.1 µF ceramic bypass capacitor between VCC and GND, placed near the IC, to suppress supply noise and prevent logic glitches. Additionally, each open-collector output (1Y, 2Y) requires an external pull-up resistor to the load supply voltage (e.g., 24 V). Unused inputs (1A, 1B, 2A, 2B) must be tied to VCC or GND - floating inputs may cause undefined output states in the SN75451BD.