## Technical Overview: IDT74FCT373C The **IDT74FCT373C** is a high-speed, low-power CMOS octal transparent latch built with advanced dual-metal CMOS technology. It is part of the 74FCT series, designed to be pin-compatible with standard TTL logic while offering significantly lower power consumption and higher speed. --- ### 1. Key Specifications The following table summarizes the electrical and operational characteristics of the device: | Parameter | Specification | | :--- | :--- | | **Logic Family** | FCT (Fast CMOS TTL-Compatible) | | **Logic Function** | Octal Transparent Latch (3-State) | | **Supply Voltage (Vcc)** | 4.5V to 5.5V | | **Input Type** | TTL Compatible | | **Output Type** | 3-State (High Impedance capability) | | **Propagation Delay** | ~5.2 ns (Grade C) | | **Quiescent Current** | 5 µA (Typical) | | **Output Drive (Ioh/Iol)** | -15 mA / 64 mA | --- ### 2. Functional Description The device consists of eight D-type latches with 3-state outputs. It operates based on two primary control signals: 1. **Latch Enable (LE):** * When **High**, the latch is "transparent"—the outputs ($Q_n$) follow the data inputs ($D_n$). * When **Low**, the data present at the inputs at the time of the high-to-low transition is latched and held. 2. **Output Enable ($\overline{OE}$):** * When **Low**, the latched data is available at the outputs. * When **High**, the outputs are placed in a high-impedance state (Hi-Z), allowing multiple devices to share a single bus. --- ### 3. Pin Configuration The IDT74FCT373C typically comes in a 20-pin package (DIP, SOIC, or QSOP). | Pin Name | Description | | :--- | :--- | | **$D_0$ - $D_7$** | 8-Bit Data Inputs | | **$Q_0$ - $Q_7$** | 8-Bit 3-State Outputs | | **LE** | Latch Enable Input | | **$\overline{OE}$** | Output Enable (Active Low) | | **Vcc / GND** | Power Supply and Ground | --- ### 4. Comparison of FCT Grades The "C" suffix in `IDT74FCT373C` denotes the speed grade. IDT produces this part in different performance tiers: * **74FCT373 (Standard):** Baseline speed. * **74FCT373A:** Faster than standard. * **74FCT373C:** **Ultra-fast** version (lowest propagation delay). --- ### 5. Application Usage The 74FCT373C is primarily used in high-performance digital systems for: * **Bus Buffering:** Interfacing microprocessors with memory or I/O. * **Address Latches:** Holding memory addresses in multiplexed address/data bus systems. * **Temporary Data Storage:** Storing data between different clock domains. ---