## SL74HC393D: Dual 4-Stage Binary Ripple Counter The **SL74HC393D** is a high-speed CMOS device. It consists of two independent 4-stage binary ripple counters (total of 8 bits) with individual Clock ($CP$) and Master Reset ($MR$) inputs. ### 1. Key Specifications and Features | Parameter | Value / Description | | :--- | :--- | | **Logic Family** | High-Speed CMOS (74HC) | | **Function** | Dual 4-Bit Binary Ripple Counter | | **Supply Voltage ($V_{CC}$)** | 2.0V to 6.0V | | **Output Current** | 5.2 mA | | **Max Frequency ($f_{max}$)** | ~50 MHz (at 6V) | | **Operating Temperature** | -55°C to +125°C | | **Package Type** | SOIC-14 (indicated by the 'D' suffix) | --- ### 2. Internal Architecture and Pinout The chip contains two identical, independent counters. Each counter has four T-type flip-flops internally connected to perform a divide-by-2, 4, 8, and 16 function. #### Pin Configuration Table | Pin Number | Symbol | Function | | :--- | :--- | :--- | | 1 | 1CP | Clock Input, Counter 1 (Negative edge triggered) | | 2 | 1MR | Master Reset, Counter 1 (Active HIGH) | | 3, 4, 5, 6 | 1Q0 - 1Q3 | Parallel Outputs, Counter 1 | | 7 | GND | Ground (0V) | | 8, 9, 10, 11| 2Q3 - 2Q0 | Parallel Outputs, Counter 2 | | 12 | 2MR | Master Reset, Counter 2 (Active HIGH) | | 13 | 2CP | Clock Input, Counter 2 (Negative edge triggered) | | 14 | $V_{CC}$ | Positive Supply Voltage | --- ### 3. Functional Logic 1. **Clocking ($CP$):** The counter advances on the **HIGH-to-LOW** transition (negative edge) of the clock input. Because it is a "ripple" counter, each stage's output serves as the clock for the next stage, leading to a small propagation delay between bits. 2. **Reset ($MR$):** A HIGH level on the Master Reset pin overrides the clock and asynchronously clears all flip-flops, setting all $Q$ outputs to LOW. 3. **Counting Sequence:** It follows a standard binary sequence ($0000$ to $1111$). --- ### 4. Typical Applications * **Frequency Division:** Dividing a high-frequency clock signal by powers of 2 (up to $2^8$ if both counters are cascaded). * **Time Delay Generation:** Creating specific intervals in digital circuits. * **Event Counting:** Tracking pulses from sensors or user inputs. * **Address Generation:** Providing sequential addresses for memory or multiplexers. --- ### 5. Cascading Example To create an 8-bit counter ($0$ to $255$), you can connect the components as follows: ```text Clock Source -> 1CP 1Q3 (MSB of Counter 1) -> 2CP (Clock for Counter 2) ``` *In this configuration, Counter 2 increments every time Counter 1 rolls over from 15 back to 0.*