## Technical Overview of the CD74ACT05E The **CD74ACT05E** is a high-speed CMOS logic integrated circuit. Specifically, it contains **six independent inverters with open-drain outputs**. It belongs to the "ACT" series, meaning it is compatible with TTL (Transistor-Transistor Logic) voltage levels but utilizes CMOS technology for lower power consumption. --- ### Key Specifications | Feature | Description | | :--- | :--- | | **Logic Family** | CD74ACT (Advanced CMOS, TTL-Compatible) | | **Logic Type** | Inverter (NOT Gate) | | **Output Type** | Open-Drain | | **Number of Elements** | 6 (Hex Inverter) | | **Voltage Supply (VCC)** | 4.5V to 5.5V | | **Package Type** | PDIP-14 (Plastic Dual In-Line Package) | | **Operating Temperature** | -55°C to 125°C | --- ### Understanding the "Open-Drain" Feature Unlike standard push-pull outputs, the CD74ACT05E uses **open-drain** outputs. * **Active Low:** When the input is High, the output pulls to Ground (Low). * **High Impedance (Hi-Z):** When the input is Low, the output transistor is turned off. * **Requirement:** To achieve a "High" logic level at the output, an external **pull-up resistor** must be connected between the output pin and the desired voltage rail. --- ### Pin Configuration (PDIP-14) ```text +---U---+ 1A | 1 14| VCC 1Y | 2 13| 6A 2A | 3 12| 6Y 2Y | 4 11| 5A 3A | 5 10| 5Y 3Y | 6 9| 4A GND | 7 8| 4Y +-------+ ``` --- ### Common Applications 1. **Wired-AND Functions:** Multiple open-drain outputs can be connected to a single pull-up resistor. If any inverter output goes Low, the entire line goes Low. 2. **Level Shifting:** Because the output is open-drain, it can be pulled up to a different voltage level (e.g., pulling a 5V logic signal up to 12V), provided the voltage does not exceed the chip's maximum ratings. 3. **Driving LEDs/Relays:** The outputs can sink current effectively, making them useful for driving small loads directly to ground. --- ### Comparison: ACT vs. HC Series | Parameter | 74HC05 (High-Speed CMOS) | 74ACT05 (Advanced CMOS TTL) | | :--- | :--- | :--- | | **Input Thresholds** | CMOS levels (scaled to VCC) | TTL levels (fixed) | | **Speed** | Moderate | Very High (Fast propagation) | | **Compatibility** | Standard CMOS | Designed to interface with TTL | ---