## PI74FCT240T: Electronic Specifications and Overview The **PI74FCT240T** is a high-speed, low-power CMOS Octal Buffer/Line Driver with 3-state outputs. It is designed specifically to improve the performance and density of 3-state memory address drivers, clock drivers, and bus-oriented receivers and transmitters. --- ### 1. Key Features and Functions * **Logic Function:** It consists of two 4-bit buffers with independent output-enable ($\overline{OE}$) controls. * **Inverting Outputs:** This specific model (240) provides inverting outputs, meaning the logic state is flipped from input to output. * **3-State Capability:** Outputs can be placed in a high-impedance state, allowing multiple devices to share the same bus lines. * **Low Power:** Uses CMOS technology to ensure low static power consumption while maintaining TTL speed. --- ### 2. Technical Specifications The following table outlines the typical electrical characteristics of the PI74FCT240T: | Parameter | Description | Typical Value | | :--- | :--- | :--- | | **$V_{CC}$** | Supply Voltage Range | 4.75V to 5.25V | | **$V_{IH}$** | High-level Input Voltage | 2.0V (Min) | | **$V_{IL}$** | Low-level Input Voltage | 0.8V (Max) | | **$I_{OH}$** | Output High Current | -15mA to -32mA | | **$I_{OL}$** | Output Low Current | 48mA to 64mA | | **$t_{PD}$** | Propagation Delay | 3.2ns - 4.8ns (Grade dependent) | | **Package** | Available Housing | QSOP, SOIC, SSOP | --- ### 3. Pin Configuration Overview The device usually comes in a 20-pin package. Below is a simplified representation of the pin logic: | Pin Type | Name | Description | | :--- | :--- | :--- | | **Inputs** | $D_{Ax}, D_{Bx}$ | Data inputs for the two 4-bit sections. | | **Outputs** | $\overline{O}_{Ax}, \overline{O}_{Bx}$ | Inverted data outputs. | | **Control** | $\overline{OE}_A, \overline{OE}_B$ | Active-low output enable pins. | | **Power** | $V_{CC}, GND$ | Power supply and Ground pins. | --- ### 4. Typical Application Circuit When using this part in a digital system, it is often used as a bus interface to drive heavy capacitive loads. ```cpp // Logic Truth Table for one 4-bit section // OE (Low) + Input (High) -> Output (Low) // OE (Low) + Input (Low) -> Output (High) // OE (High) -> Output (High-Z / Floating) ``` ### 5. Selection Variants The "T" in the suffix usually denotes the speed grade or specific temperature range. Pericom (the original manufacturer, now part of Diodes Inc.) categorized these as: * **FCT240T:** Standard Speed. * **FCT240AT:** Fast Speed. * **FCT240CT:** Ultra-Fast Speed. ---