The **U74CBT3251G-R16-R** is a high-speed CMOS 8-to-1 multiplexer/demultiplexer (bus switch) manufactured by Unisonic Technologies (UTC). It is designed for high-speed switching and low power consumption. --- ## 1. Core Specifications and Technical Data | Parameter | Description | | :--- | :--- | | **Part Number** | U74CBT3251G-R16-R | | **Logic Type** | 8:1 Multiplexer / Demultiplexer | | **Switch Type** | CMOS Bus Switch | | **Supply Voltage ($V_{CC}$)** | 4.0V to 5.5V | | **ON-State Resistance ($R_{on}$)** | ~5Ω (Typical) | | **Propagation Delay** | < 0.25 ns (Negligible) | | **Package Type** | SSOP-16 / QSOP-16 | | **Operating Temperature** | -40°C to +85°C | --- ## 2. Key Features * **Low ON-Resistance:** With a typical resistance of 5Ω, it ensures minimal signal distortion and voltage drop across the switch. * **Bidirectional Operation:** It allows signals to flow in both directions (A to B or B to A), making it ideal for bus-based architectures. * **Near-Zero Propagation Delay:** Because it acts as a mechanical switch rather than a buffered logic gate, the delay is extremely low. * **Power-Down High-Impedance:** When $V_{CC}$ is 0V, the device is in a high-impedance state, preventing current backflow. --- ## 3. Function Table The device selects one of eight I/O pins (B1-B8) to connect to a single common I/O pin (A) based on the binary input of the Select pins (S0, S1, S2) and the Output Enable ($\overline{OE}$) pin. | $\overline{OE}$ | S2 | S1 | S0 | Function | | :---: | :---: | :---: | :---: | :--- | | L | L | L | L | A connected to B1 | | L | L | L | H | A connected to B2 | | L | H | H | H | A connected to B8 | | H | X | X | X | Disconnect (Hi-Z) | --- ## 4. Typical Applications * **Memory Interleaving:** Switching between different memory banks. * **Bus Isolation:** Separating high-speed buses to reduce capacitive loading. * **Signal Routing:** Directing high-speed digital signals in telecommunications and computing. * **Voltage Translation:** Used in mixed 3.3V/5V environments (though limited compared to dedicated level shifters). --- ## 5. Package and Marking The suffix **R16-R** generally refers to: * **R16:** 16-pin count package (usually SSOP or TSSOP). * **R:** Tape and Reel packaging for automated PCB assembly.