## CD74ACT05: Hex Inverter with Open-Drain Outputs The **CD74ACT05** is a high-speed CMOS logic integrated circuit containing six independent inverters. It is part of the "ACT" series, meaning it features TTL-compatible inputs and operates at advanced CMOS speeds. ### 1. Key Technical Specifications | Parameter | Value | | :--- | :--- | | **Logic Family** | ACT (Advanced CMOS with TTL levels) | | **Logic Function** | Inverter (NOT Gate) | | **Output Type** | Open-Drain | | **Number of Elements** | 6 (Hex) | | **Supply Voltage (Vcc)** | 4.5V to 5.5V | | **Input Logic Low (Max)** | 0.8V | | **Input Logic High (Min)** | 2.0V | | **Propagation Delay** | ~5ns to 8ns (typical at 5V) | --- ### 2. Functional Description Unlike standard inverters that have a "Push-Pull" output, the CD74ACT05 features **Open-Drain outputs**. - **Logic Low (0):** When the input is High, the output transistor turns on, pulling the output pin to Ground (Vss). - **Logic High (Z):** When the input is Low, the output transistor turns off, putting the output in a High-Impedance state. - **Pull-up Resistor:** To achieve a "High" voltage level, an external pull-up resistor must be connected between the output pin and the desired voltage rail ($V_{OH}$). --- ### 3. Pin Configuration The device is typically housed in a 14-pin DIP or SOIC package. | Pin Number | Symbol | Description | | :--- | :--- | :--- | | 1, 3, 5, 9, 11, 13 | 1A - 6A | Data Inputs | | 2, 4, 6, 8, 10, 12 | 1Y - 6Y | Data Outputs (Open-Drain) | | 7 | GND | Ground | | 14 | Vcc | Positive Supply (5V) | --- ### 4. Primary Applications * **Wired-AND Logic:** Multiple open-drain outputs can be connected together to a single pull-up resistor. If any one inverter output goes Low, the entire line goes Low. * **Level Shifting:** Since the output is open-drain, it can be pulled up to a voltage different from Vcc (e.g., pulling a 5V logic signal up to 12V). * **Driving LED/Relays:** Useful for sinking current from loads connected to a higher voltage supply. * **Bus Interfacing:** Often used in systems where multiple devices need to share a single signal line. ---