Texas Instruments SN75451BDR

Overview

SN75451BDR from Texas Instruments is a dual-peripheral AND 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 SN75451BDR datasheet, SN75451BDR pinout, SN75451BDR application, or SN75451BDR equivalent, key selection criteria include its AND logic function, SOIC-8 package thermal performance (R_θJA = 122.2°C/W), latch-up immunity at 20 V/300 mA, and compatibility with 5 V logic supply rails.

Technical Context

The SN75451BDR implements two independent AND-gated npn transistor drivers with internally connected logic gates and emitter-follower output stages. Each channel accepts TTL-level inputs (V_IL ≤ 0.8 V, V_IH ≥ 2 V) and drives loads via open-collector outputs capable of sinking up to 300 mA continuously.

It uses internal base-emitter resistors (≤500 Ω) to ensure latch-up freedom and supports fast switching with t_PLH/t_PHL ≤ 25 ns (V_CC = 5 V, T_A = 25°C, I_O ≈ 200 mA). The device requires no external pull-ups on outputs and is optimized for direct connection to inductive or resistive loads.

Key Specifications

Pinout & Package

SN75451BDR 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 is R_θJA = 122.2°C/W, requiring minimal copper area for thermal management in typical PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN75451BP and SN75452BDR, the SN75451BDR offers surface-mount reliability and automated assembly compatibility in SOIC-8, while retaining identical AND functionality and 300 mA drive strength - making it optimal for volume production of compact control boards.

Availability

SN75451BDR is available at Aetrix Electronics and suitable for lamp drivers, LED drivers, relay interfaces, and memory address buffering requiring stable component supply and long-term industrial availability.

Supply support for SN75451BDR 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 delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The SN7545xB family was engineered specifically for TTL-system peripheral interfacing - providing robust, latch-up-free, high-current driver capability in compact packages for legacy and modern control applications.

FAQ

What logic function does the SN75451BDR implement?

The SN75451BDR implements a dual AND gate driver: each channel activates its open-collector output only when both corresponding inputs (1A/1B or 2A/2B) are logic high. This behavior is confirmed in the device function table (Table 8-1) and logic diagram (Figure 8-1) of the official TI datasheet. The SN75451BDR does not perform NAND, OR, or NOR functions - those are handled by other members of the SN7545xB family like SN75452BDR or SN75453BDR.

Can SN75451BDR drive a 24 V relay coil directly?

Yes, the SN75451BDR can directly drive a 24 V relay coil provided the coil's steady-state current remains ≤300 mA and inrush current is managed. Its output withstands 30 V off-state voltage and sinks up to 300 mA continuously. A flyback diode must be placed across the coil, and the V_CC pin must be decoupled with a 0.1 µF capacitor. The SN75451BDR's latch-up immunity at 20 V/300 mA ensures safe operation during relay turn-off transients.

What is the maximum recommended operating temperature for SN75451BDR?

The SN75451BDR is characterized for operation from 0°C to 70°C ambient temperature, as stated in the "Device Comparison Table" and "Recommended Operating Conditions" sections of the TI datasheet. Exceeding 70°C ambient may cause thermal shutdown or parametric drift; derating is required above this range. For extended temperature operation, consider the military-grade SN55451B variant rated from –55°C to 125°C.

Does SN75451BDR require external pull-up resistors on its outputs?

Yes, SN75451BDR requires external pull-up resistors on both 1Y and 2Y outputs because they are open-collector. Without pull-ups, outputs cannot assert a logic-high voltage. Typical values range from 1 kΩ to 10 kΩ depending on load capacitance and speed requirements. The datasheet Figure 9-1 shows explicit use of pull-up resistors in the reference application circuit.

Is SN75451BDR pin-compatible with SN75451BD?

Yes, SN75451BDR and SN75451BD share identical SOIC-8 (D) package dimensions, pinout, and electrical specifications - differing only in packaging format (tape-and-reel vs. tube). Both have identical marking "75451B", same RoHS compliance, Level-1 moisture sensitivity, and 0°C to 70°C temperature rating. They are functionally and mechanically interchangeable in PCB designs.