Texas Instruments SN74LS244DBRG4

Overview

SN74LS244DBRG4 from Texas Instruments is an octal non-inverting 3-state buffer/line driver in SSOP-20 package, designed for memory address and bus driving applications. It features two independent 4-bit channels, 15 ns maximum propagation delay at 5 V, 24 mA output sink current, and PNP inputs that reduce DC loading on driven buses.

For engineers reviewing the SN74LS244DBRG4 datasheet, SN74LS244DBRG4 pinout, SN74LS244DBRG4 application, or SN74LS244DBRG4 equivalent, key selection criteria include 3-state bus isolation capability, TTL-compatible input thresholds (VIH = 2 V, VIL = 0.7 V), thermal resistance (RθJA = 94.3°C/W), and compatibility with mixed 3.3-V/5-V logic systems.

Technical Context

The SN74LS244DBRG4 implements two independent 4-bit non-inverting buffers, each controlled by a dedicated active-low output-enable (G) input (Pin 1 and Pin 19). Its PNP input structure reduces DC loading on upstream drivers, while built-in input hysteresis improves noise immunity on shared bus lines.

Each channel operates with symmetrical 3-state control: when G is low, data passes from A-side inputs to Y-side outputs; when G is high, all four outputs enter high-impedance state. The device supports terminated line driving down to 133 Ω and meets standard TTL voltage thresholds under recommended operating conditions (VCC = 4.75–5.25 V, TA = 0–70°C).

Key Specifications

Pinout & Package

SN74LS244DBRG4 uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch and nominal body size 7.20 mm × 5.30 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal non-inverting 3-state buffer applications.

Compared with SN74LS240DBR, SN74LS244DBRG4 provides direct non-inverting signal routing without logic inversion overhead; compared with SN74HC244PWR, it delivers superior noise immunity and proven 133-Ω line driving capability in legacy 5-V industrial bus architectures.

Availability

SN74LS244DBRG4 is available at Aetrix Electronics and suitable for memory address buffering, LED display driving, network switch backplane interfacing, and industrial I/O expansion requiring stable component supply across long-lifecycle embedded programs.

Supply support for SN74LS244DBRG4 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

SN74LS244DBRG4 belongs to TI's legacy LS (Low-power Schottky) logic family, engineered specifically for high-density, high-fan-out bus interface applications in memory systems, instrumentation, and industrial control equipment.

FAQ

What is the function of Pin 19 (2G) on the SN74LS244DBRG4?

Pin 19 is the active-low output-enable input for Channel 2. When 2G is low, the four 2A inputs (Pins 11, 13, 15, 17) are passed non-invertingly to the corresponding 2Y outputs (Pins 3, 5, 7, 9). When 2G is high, all four 2Y outputs enter high-impedance state. This enables independent control of Channel 2's bus participation without affecting Channel 1, a key feature used in SN74LS244DBRG4-based memory and I/O expansion designs.

Can SN74LS244DBRG4 interface safely with 3.3-V microcontrollers?

Yes. SN74LS244DBRG4 inputs tolerate voltages down to 2 V and are compatible with 3.3-V logic levels. Its VIH minimum is 2 V and VIL maximum is 0.7 V, allowing direct connection to 3.3-V CMOS outputs while operating at 5-V VCC. This mixed-voltage capability eliminates level shifters in SN74LS244DBRG4-based systems bridging legacy 5-V peripherals and modern low-voltage controllers.

What is the maximum capacitive load SN74LS244DBRG4 can drive while maintaining 15 ns propagation delay?

SN74LS244DBRG4 maintains its 15 ns maximum tpd specification under RL = 667 Ω and CL = 45 pF loading conditions, per the official switching characteristics table. Exceeding 45 pF increases propagation delay nonlinearly; for loads >50 pF, designers should verify timing margins using the actual board trace capacitance and consider adding series termination or reducing trace length to preserve SN74LS244DBRG4's specified timing performance.

Does SN74LS244DBRG4 require pull-up resistors on its G inputs?

Yes. To ensure outputs remain in high-impedance state during power-up or power-down sequences, both 1G (Pin 1) and 2G (Pin 19) must be tied to VCC through pull-up resistors. The minimum resistor value depends on the current-sinking capability of the controlling logic; TI recommends values between 4.7 kΩ and 10 kΩ for robust noise immunity and fast enable/disable transitions in SN74LS244DBRG4 applications.

How does the PNP input structure benefit SN74LS244DBRG4 in bus applications?

The PNP input structure reduces DC input loading to approximately 0.2 mA per input, significantly lowering the cumulative fan-out burden on upstream drivers. In SN74LS244DBRG4-based memory address buses with multiple receivers, this allows more devices per bus segment without violating TTL fan-out limits, improves signal rise/fall times, and reduces power dissipation in source drivers-key advantages in dense industrial backplane designs.