## AM25LS374APC: Technical Overview The **AM25LS374APC** is a high-performance, low-power Schottky (LS) Octal D-Type Flip-Flop with 3-state outputs. It was originally manufactured by Advanced Micro Devices (AMD). --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Logic Family** | 25LS (Low Power Schottky variant) | | **Function** | Octal D-Type Edge-Triggered Flip-Flop | | **Output Type** | 3-State (Tri-state) | | **Package** | 20-Pin Plastic DIP (Dual In-line Package) | | **Operating Voltage** | 4.75V to 5.25V (Standard TTL) | | **Propagation Delay** | ~14ns (Typical) | | **Clock Frequency** | Up to 50 MHz | --- ### 2. Pinout Description The device features 20 pins, designed for 8-bit bus-oriented applications. | Pin Number | Symbol | Description | | :--- | :--- | :--- | | 1 | $\overline{OE}$ | Output Enable (Active Low) | | 2, 5, 6, 9, 12, 15, 16, 19 | $Q_0 - Q_7$ | 8-bit Data Outputs | | 3, 4, 7, 8, 13, 14, 17, 18 | $D_0 - D_7$ | 8-bit Data Inputs | | 11 | $CP$ | Clock Pulse (Positive Edge Triggered) | | 10 | $GND$ | Ground | | 20 | $V_{CC}$ | Supply Voltage | --- ### 3. Functional Operation The AM25LS374APC acts as an 8-bit storage register. Its behavior is governed by the Clock ($CP$) and Output Enable ($\overline{OE}$) signals: * **Data Latched:** Data at the $D$ inputs is transferred to the $Q$ outputs on the **Positive-Going (Low-to-High)** transition of the clock pulse. * **3-State Outputs:** * When $\overline{OE}$ is **LOW**, the stored data is present on the output pins. * When $\overline{OE}$ is **HIGH**, the outputs are in a high-impedance state (Hi-Z), effectively disconnecting the device from the bus. * **Edge-Triggered:** Unlike a latch, this flip-flop only samples input at the precise moment of the clock edge, making it more stable against input noise between cycles. --- ### 4. Comparison: '374 vs '373 While both are octal registers, they differ in timing: * **'374 (Flip-Flop):** Data is captured only at the clock edge. * **'373 (Latch):** Data flows through transparently while the enable pin is high and "freezes" when it goes low. --- ### 5. Application Example The AM25LS374 is commonly used as an **Output Port** for microprocessors or as a **Buffer/Register** for data synchronization between two different clock domains on a shared data bus.