The **74FR244PC** is a high-speed, low-power Octal Buffer/Line Driver with 3-state outputs. It belongs to the **FAST (Fairchild Advanced Schottky TTL)** series, specifically designed to drive high-capacitance loads or low-impedance backplanes. --- ## 1. Key Specifications The following table summarizes the primary electrical and physical characteristics of the 74FR244PC. | Parameter | Specification | | :--- | :--- | | **Logic Family** | FR (FAST) | | **Function** | Buffer / Line Driver | | **Number of Channels** | 8 (Split into two 4-bit groups) | | **Output Type** | 3-State (High, Low, High-Impedance) | | **Supply Voltage ($V_{CC}$)** | 4.5V to 5.5V (Standard 5V TTL) | | **Package Type** | PDIP-20 (Plastic Dual In-line Package) | | **Propagation Delay** | Approx. 3.5ns - 5.0ns | | **Operating Temperature** | 0°C to +70°C | --- ## 2. Pin Configuration and Internal Logic The 74FR244 consists of eight non-inverting buffers organized into two sets of four. Each set is controlled by an active-low Output Enable ($\overline{OE}$) pin. ### Logic Symbol Table | $\overline{OE}$ (Input) | D (Data Input) | Y (Output) | Mode | | :---: | :---: | :---: | :--- | | L | L | L | Transparent (Low) | | L | H | H | Transparent (High) | | H | X | Z | High-Impedance (Disabled) | * **L** = Low Voltage Level * **H** = High Voltage Level * **X** = Irrelevant (Don't Care) * **Z** = High Impedance (Disconnected) --- ## 3. Core Features ### 3-State Outputs The outputs can be put into a high-impedance state, effectively "disconnecting" them from the circuit. This allows multiple devices to share the same bus lines without causing electrical conflicts (bus contention). ### High Drive Capability The "FR" series is optimized for high output current, making it ideal for: * Driving long ribbon cables. * Driving memory arrays (SRAM/DRAM address lines). * Acting as a buffer between a low-power CPU and heavy peripheral loads. ### Reduced Noise The internal circuitry is designed to minimize ground bounce and electromagnetic interference (EMI), which are common issues in high-speed switching environments. --- ## 4. Typical Application Example In a microprocessor system, the 74FR244 is often used as a **Bus Buffer**. ```c // Conceptual Logic for controlling the 74FR244 via a Microcontroller if (Bus_Requested == TRUE) { digitalWrite(OE_PIN, LOW); // Activate the buffer to let data through } else { digitalWrite(OE_PIN, HIGH); // Isolate the device from the bus } ``` ---