The **U74CBT3257L-R16-R** is a high-speed CMOS 1-of-2 multiplexer/demultiplexer (switch) designed for low On-state resistance and high-speed signal routing. It is commonly used in bus switching, signal gating, and voltage translation applications. --- ### ## Technical Specifications Overview | Parameter | Specification | Description | | :--- | :--- | :--- | | **Type** | 1-of-2 Mux/Demux | Can route 1 input to 2 outputs or 2 inputs to 1 output per channel. | | **Channels** | Quad (4-channel) | Contains four independent 1-of-2 switches. | | **Logic Family** | CBT (Crossbar Technology) | Optimized for high-speed bus switching. | | **Supply Voltage ($V_{CC}$)** | 4.0V to 5.5V | Compatible with standard 5V systems. | | **On-State Resistance ($R_{on}$)** | ~5$\Omega$ (Typical) | Minimal signal degradation/attenuation. | | **Propagation Delay** | $\leq$ 0.25 ns | Near-instantaneous switching. | | **Package** | TSSOP-16 | Compact surface-mount package. | --- ### ## Functional Description The U74CBT3257L consists of four individual sets of switches. Each set has a common terminal (A) and two selectable ports (B1 and B2). 1. **Select Pin (S):** Chooses between the B1 or B2 port. 2. **Output Enable ($\overline{OE}$):** When low (L), the switch is active. When high (H), the device enters a high-impedance state (Z), effectively disconnecting the bus. #### ### Truth Table | $\overline{OE}$ | S | Function | | :---: | :---: | :--- | | L | L | A Port connected to B1 Port | | L | H | A Port connected to B2 Port | | H | X | Disconnect (High-Z) | --- ### ## Key Electronic Features * **Low Power Consumption:** Uses CMOS technology to maintain low static power dissipation. * **Voltage Translation:** While it operates at 5V, it can be used to facilitate 5V to 3.3V translation if the input levels are managed correctly. * **Bi-directional Data Flow:** Because it is a passive switch (FET-based), data can flow from A to B or from B to A without additional control logic. * **Zero Propagation Delay:** Due to the low $R_{on}$, the device adds virtually no timing delay to the bus signals. --- ### ## Typical Applications * **Memory Interleaving:** Switching between two different banks of RAM. * **Bus Isolation:** Disconnecting a subsystem from a main bus to reduce capacitive loading or during power-down states. * **Multiplexing:** Routing multiple sensor inputs to a single ADC pin on a microcontroller. * **Video/Audio Signal Routing:** High-speed switching for low-bandwidth analog or high-speed digital signals.