## ADM824ZYKS-R7: Microprocessor Supervisory Circuit The **ADM824ZYKS-R7** is a high-precision supervisory circuit manufactured by **Analog Devices**. It is designed to monitor power supply voltage levels in microprocessor-based systems and provide a reset signal to ensure the system starts or restarts in a controlled manner. --- ### 1. Core Technical Specifications | Parameter | Specification | | :--- | :--- | | **Function** | Microprocessor Supervisor (Voltage Monitor & Watchdog) | | **Threshold Voltage ($V_{TH}$)** | 2.32V (Standard for "Z" suffix) | | **Reset Timeout Period** | 140 ms (minimum) | | **Watchdog Timeout** | 1.6 seconds (typical) | | **Output Type** | Push-Pull (Active High and Active Low) | | **Supply Voltage ($V_{CC}$)** | 1.0V to 5.5V | | **Package Type** | SC-70-5 (Lead-Free) | | **Operating Temperature** | -40°C to +85°C | --- ### 2. Key Electronic Features The ADM824 integrates three primary functions into a single small-footprint component: #### A. Precision Voltage Monitoring The device monitors the $V_{CC}$ line. If the voltage falls below the factory-set threshold (2.32V for the 'Z' model), the device triggers a **Reset**. This prevents the microprocessor from executing code at unreliable voltage levels. #### B. Watchdog Timer (WDT) To prevent system "hangs" or software loops, the device features a watchdog input (WDI). * The microprocessor must toggle the WDI pin within a specific window (1.6s). * If the processor fails to toggle the pin (due to a crash), the ADM824 issues a reset. #### C. Dual Reset Outputs Unlike simpler monitors, the ADM824 provides two complementary signals: 1. **RESET (Active Low):** Standard for most microcontrollers. 2. **RESET (Active High):** Useful for specific logic circuits or power-down sequences. --- ### 3. Pin Configuration (SC-70 Package) | Pin No. | Name | Function | | :---: | :--- | :--- | | 1 | **RESET** | Active-Low Reset Output. | | 2 | **GND** | Ground Reference. | | 3 | **WDI** | Watchdog Input. Triggers reset if not toggled within 1.6s. | | 4 | **RESET** | Active-High Reset Output. | | 5 | **Vcc** | Power Supply Input / Monitored Voltage. | --- ### 4. Typical Application Diagram In a standard circuit, the ADM824 sits between the power source and the MCU: ```markdown [Power Supply 3.3V] ----+---- [Vcc (Pin 5)] | +---- [MCU Vcc] [ADM824] (Pin 1) RESET -----------> [MCU Reset Pin] (Pin 3) WDI <----------- [MCU I/O Pin (Heartbeat)] (Pin 2) GND ----------- [Common Ground] ``` --- ### 5. Part Number Breakdown (ADM824ZYKS-R7) * **ADM824**: Product Series (Supervisor with Watchdog). * **Z**: Threshold Voltage Code (2.32V). * **YKS**: Package Code (SC-70 / SOT-323). * **R7**: Tape and Reel Packaging (7-inch reel).