## SN74LS393DRE4: Technical Overview The **SN74LS393DRE4** is a high-speed CMOS/TTL compatible integrated circuit consisting of two independent 4-bit binary counters. It is part of the "Low-power Schottky" (LS) family, widely used for frequency division and digital counting applications. ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Logic Family** | LS-TTL (Low-power Schottky) | | **Logic Type** | Dual 4-Bit Binary Counter | | **Operating Voltage (Vcc)** | 4.75V to 5.25V | | **Package Type** | SOIC-14 (Small Outline IC) | | **Max Clock Frequency** | 35 MHz (Typical) | | **Operating Temperature** | 0°C to 70°C | | **Pin Count** | 14 Pins | --- ### 2. Internal Structure and Functionality The device contains **two separate 4-bit ripple counters**. Because it is a ripple counter, the clock triggers the first flip-flop, and each subsequent flip-flop is triggered by the output of the previous one. * **Clock Inputs (1A, 2A):** These are negative-edge triggered. The counter increments on the High-to-Low transition of the clock signal. * **Clear Inputs (1CLR, 2CLR):** These are active-high inputs. When a Clear pin is pulled High, all four bits of that specific counter are reset to zero (0000). * **Outputs (QA, QB, QC, QD):** These represent the 4-bit binary count, where QA is the Least Significant Bit (LSB) and QD is the Most Significant Bit (MSB). --- ### 3. Pin Configuration | Pin Number | Symbol | Description | | :--- | :--- | :--- | | 1 | 1A | Clock Input Counter 1 | | 2 | 1CLR | Clear Input Counter 1 | | 3, 4, 5, 6 | 1QA - 1QD | Outputs Counter 1 | | 7 | GND | Ground | | 8, 9, 10, 11 | 2QD - 2QA | Outputs Counter 2 | | 12 | 2CLR | Clear Input Counter 2 | | 13 | 2A | Clock Input Counter 2 | | 14 | Vcc | Supply Voltage | --- ### 4. Part Number Breakdown (Suffix Meaning) Understanding the suffix is critical for procurement and manufacturing: * **SN74:** Standard commercial temperature range prefix. * **LS:** Low-power Schottky logic family. * **393:** Specific device function (Dual 4-bit binary counter). * **D:** Package type (SOIC - Small Outline Integrated Circuit). * **R:** Indicates "Reel" (Tape and Reel packaging). * **E4:** Lead-free (RoHS compliant) and "Green" material construction. --- ### 5. Common Applications * **Frequency Dividers:** By using the QD output, the input clock frequency can be divided by 16. * **Digital Clocks:** Used in timing circuits to count seconds, minutes, or hours. * **Address Generators:** Useful in simple memory addressing systems. * **Delay Lines:** Creating specific timing delays in logic circuits.