Texas Instruments SN75451BP

Overview

SN75451BP from Texas Instruments is a dual-channel AND-gate peripheral driver IC designed for high-current, high-speed switching in TTL-compatible 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 SN75451BP datasheet, SN75451BP pinout, SN75451BP application, or SN75451BP equivalent, key selection criteria include its AND logic function, 300 mA continuous output current capability, 30 V off-state voltage rating, open-collector topology, and PDIP-8 package compatibility with through-hole prototyping and industrial control boards.

Technical Context

The SN75451BP integrates two independent AND-gate logic circuits whose outputs drive NPN transistor stages with internal base resistors. Each channel functions as a high-side switch referenced to VCC, pulling the output low (to GND) only when both inputs are high - enabling precise enable-controlled driving of external loads.

Its diode-clamped TTL inputs ensure robust noise immunity and compatibility with standard 5 V logic families, while the open-collector configuration allows wired-OR interfacing and flexible pull-up voltage selection up to 30 V - critical for mixed-voltage system interfacing without level shifters.

Key Specifications

Pinout & Package

SN75451BP uses an 8-pin PDIP (Plastic Dual In-line Package) with 9.81 mm × 6.35 mm body size and through-hole mounting. Pin spacing follows standard 0.1-inch grid.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN75451BD and SN75452BP, the SN75451BP offers through-hole PDIP packaging ideal for manual assembly and testing, retains identical AND functionality critical for positive-logic enable paths, and avoids NAND-based signal inversion that would require redesign of upstream logic or firmware.

Availability

SN75451BP is available at Aetrix Electronics and suitable for lamp drivers, relay interfaces, and LED control applications requiring stable component supply, long-term industrial availability, and through-hole manufacturability.

Supply support for SN75451BP 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 solutions for industrial, automotive, and communications markets.

The SN7545xB family was designed specifically to replace legacy SN75450-series drivers with enhanced latch-up immunity and consistent 300 mA drive capability - targeting cost-sensitive, high-reliability peripheral interfacing in commercial-grade systems.

FAQ

What logic function does the SN75451BP implement?

The SN75451BP implements a dual AND-gate logic function: each channel's output (1Y or 2Y) goes low (active sink) only when both corresponding inputs (1A/1B or 2A/2B) are high. This behavior is confirmed in the device function table and logic diagram in the official TI datasheet. The SN75451BP does not perform NAND, OR, or NOR operations - those are implemented by other members of the SN7545xB family such as SN75452BP or SN75453BP.

Can the SN75451BP drive a 24 V relay coil directly?

Yes, the SN75451BP can drive a 24 V relay coil directly using its open-collector output configuration. Connect the relay coil between the 24 V supply and the SN75451BP output pin (e.g., 1Y), and place a flyback diode across the coil. The SN75451BP supports up to 30 V off-state voltage and 300 mA continuous sink current - well within typical 24 V relay coil requirements. Ensure the input logic levels meet TTL thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) and that unused inputs are tied to VCC or GND.

What is the maximum operating temperature range for the SN75451BP?

The SN75451BP is characterized for operation from 0°C to 70°C - the commercial temperature range. This is explicitly stated in the device comparison table and recommended operating conditions section of the TI datasheet. It is not rated for extended industrial (–40°C to 85°C) or military (–55°C to 125°C) ranges; for those, the SN55451B variant in CDIP or LCCC packages must be selected.

Does the SN75451BP require external base resistors for its output transistors?

No, the SN75451BP does not require external base resistors. Its internal schematic (Figure 8-9 in the TI datasheet) shows integrated base drive resistors - 1 kΩ and 1.6 kΩ - connected between the AND gate output and the NPN transistor base. These resistors provide appropriate biasing for 300 mA collector current under 5 V VCC, eliminating the need for external components and simplifying board layout.

How should unused inputs on the SN75451BP be handled?

Unused inputs on the SN75451BP must be tied to a valid logic level - either VCC or GND - and must never be left floating. Floating inputs can cause the internal AND gate to enter an indeterminate state, resulting in unpredictable output behavior or increased supply current. The datasheet explicitly warns against floating inputs in Section 9.2.1 and recommends connecting unused pins to VCC for a logic-high default or to GND for logic-low, depending on the desired default output state.