The **U74CBT3253L-R16-R** is a high-speed CMOS dual 1-of-4 FET multiplexer/demultiplexer. It is designed to facilitate high-speed signal switching with minimal propagation delay and low "ON" resistance. --- ### 1. Key Technical Specifications | Parameter | Description | | :--- | :--- | | **Logic Family** | CBT (Crossbar Technology) | | **Function** | Dual 4:1 Multiplexer / Demultiplexer | | **Voltage Supply Range** | 4.0V to 5.5V | | **Propagation Delay** | Low (approx. 0.25ns typical at 5V) | | **Input/Output Capacitance** | Low (helps maintain signal integrity) | | **Package Type** | TSSOP-16 / SSOP-16 (R16 suffix) | | **Operating Temperature** | -40°C to +85°C | --- ### 2. Functional Pins and Internal Structure The device consists of two independent 4-to-1 switches. Each switch is controlled by common select inputs ($S_0, S_1$) and an individual output enable ($\overline{OE}$). #### Pin Configuration Table | Pin Name | Type | Description | | :--- | :--- | :--- | | **1$\overline{OE}$, 2$\overline{OE}$** | Input | Output Enable (Active Low) | | **S0, S1** | Input | Select Inputs (Binary address) | | **1B1 - 1B4** | I/O | Port B inputs/outputs for Channel 1 | | **2B1 - 2B4** | I/O | Port B inputs/outputs for Channel 2 | | **1A, 2A** | I/O | Common Port A for Channel 1 and 2 | | **Vcc / GND** | Power | Power Supply and Ground | --- ### 3. Core Features and Benefits * **Low ON-Resistance ($R_{on}$):** Typically 5Ω, allowing signals to pass through the switch with negligible voltage drop and distortion. * **Bidirectional Operation:** Since the internal structure uses FETs (Field Effect Transistors), the data path can flow from A to B or B to A. * **Zero Propagation Delay:** Because it acts as a simple wire when "ON," it does not add the significant gate delays found in standard logic buffers. * **5V Tollerant:** While it operates at 5V, it is often used for voltage level translation or bus isolation in mixed-voltage environments. --- ### 4. Typical Applications * **Bus Switching:** Connecting multiple memory modules to a single CPU bus. * **Signal Gating:** Enabling or disabling specific data paths in a circuit. * **Voltage Translation:** Using the device to interface between different logic levels (e.g., 5V to 3.3V) by limiting $V_{cc}$. * **Resource Multiplexing:** Sharing a single peripheral (like a UART or I2C sensor) between four different controllers. --- ### 5. Truth Table (Logic Operation) | $\overline{OE}$ | S1 | S0 | Function | | :---: | :---: | :---: | :--- | | L | L | L | A Port connected to B1 Port | | L | L | H | A Port connected to B2 Port | | L | H | L | A Port connected to B3 Port | | L | H | H | A Port connected to B4 Port | | H | X | X | Disconnected (High Impedance) |