## Overview of the 74LV393D The **74LV393D** is a low-voltage CMOS device containing **two independent 4-bit binary counters** (dual 4-stage binary ripple counters). Each counter has its own Clock input ($\overline{CP}$) and a Master Reset (MR). --- ### 1. Key Technical Specifications | Parameter | Value / Range | | :--- | :--- | | **Logic Family** | 74LV (Low Voltage CMOS) | | **Supply Voltage ($V_{CC}$)** | 1.0V to 3.6V (Optimized for 3.3V) | | **Propagation Delay** | ~15ns at 3.3V | | **Output Current** | $\pm 6$ mA | | **Package Type** | SO-14 (Small Outline - 14 pins) | | **Operating Temp** | -40°C to +125°C | --- ### 2. Functional Description Each of the two counters inside the 74LV393D functions as follows: * **Clock ($\overline{CP}$):** The counter advances on the **High-to-Low transition** (falling edge) of the clock pulse. * **Outputs ($Q_0$ to $Q_3$):** These provide the binary count. $Q_0$ is the Least Significant Bit (LSB), and $Q_3$ is the Most Significant Bit (MSB). * **Master Reset (MR):** This is an **Active-High** input. When MR is set to High, it overrides the clock and asynchronously resets all counter stages to zero (Low). --- ### 3. Pin Configuration (SO-14) | Pin No. | Symbol | Description | | :--- | :--- | :--- | | 1 | 1$\overline{CP}$ | Clock Input, Counter 1 (Falling Edge) | | 2 | 1MR | Master Reset, Counter 1 (Active High) | | 3 - 6 | 1$Q_0$ - 1$Q_3$ | Parallel Outputs, Counter 1 | | 7 | GND | Ground (0V) | | 8 - 11 | 2$Q_3$ - 2$Q_0$ | Parallel Outputs, Counter 2 | | 12 | 2MR | Master Reset, Counter 2 (Active High) | | 13 | 2$\overline{CP}$ | Clock Input, Counter 2 (Falling Edge) | | 14 | $V_{CC}$ | Supply Voltage | --- ### 4. Logic Table (Per Counter) | MR (Reset) | $\overline{CP}$ (Clock) | Output State | | :--- | :--- | :--- | | **H** | X | All Outputs = L (Reset) | | **L** | $\downarrow$ | Count Advances (Binary) | | **L** | $\uparrow$ | No Change | --- ### 5. Common Applications * **Frequency Division:** By taking the output from specific $Q$ pins, you can divide the input frequency by 2, 4, 8, or 16. * **Time Delays:** Generating specific timing intervals in digital circuits. * **Counter Cascading:** The two counters can be connected in series (cascaded) to create an **8-bit ripple counter**, allowing for a count up to 255 ($2^8 - 1$). * **Low Power Systems:** Ideal for battery-operated devices due to the 74LV family's low power consumption. ---