The **ADM1818-R23AKSZ-R72** is a microprocessor supervisory circuit manufactured by Analog Devices. It is primarily designed to monitor power supply voltages in computer and digital systems, ensuring that the processor remains in a reset state during power-up or during brownout conditions. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Reset Threshold** | 2.31V (Nominal) | | **Output Type** | Open-Drain (Active Low) | | **Reset Timeout** | 150 ms (typical) | | **Supply Voltage (Vcc)** | 1.0V to 5.5V | | **Package** | SC-70 (3-lead) | | **Operating Temperature** | -40°C to +105°C | --- ### 2. Core Functional Components The internal architecture consists of several critical electronic blocks: 1. **Precision Voltage Reference:** A stable internal reference used to compare the incoming $V_{CC}$ against the 2.31V threshold. 2. **Voltage Comparator:** This component continuously monitors the supply rail. When $V_{CC}$ drops below the threshold, the comparator triggers the reset logic. 3. **Time Delay Circuit:** Once the voltage rises above the threshold, the chip does not release the reset immediately. It holds the "Reset" signal for approximately **150ms** to ensure the power supply has stabilized. 4. **Open-Drain Output Stage:** Since the output is open-drain, it requires an external **pull-up resistor** to the desired logic voltage level. This allows for "wired-OR" logic configurations. --- ### 3. Application and Usage #### Typical Circuit Connection In a standard application, the pins are connected as follows: * **Pin 1 (RESET):** Connected to the RESET input of the Microcontroller (MCU). Requires a pull-up resistor. * **Pin 2 (Vcc):** Connected to the 2.5V or 3.3V power rail being monitored. * **Pin 3 (GND):** Connected to the system ground. #### Functionality Table | Supply Condition | RESET Pin State | Logic Level | | :--- | :--- | :--- | | $V_{CC} >$ Threshold | High Impedance | High (via Pull-up) | | $V_{CC} <$ Threshold | Low (Sinking Current) | Low | | During Power-up | Low (for 150ms) | Low | --- ### 4. Part Number Breakdown (ADM1818-R23AKSZ-R7) * **ADM1818**: Base Model (Low Power Microprocessor Reset Circuit). * **R23**: 2.31V Threshold Voltage. * **AKSZ**: SC-70 Package (Lead-Free). * **R7**: Refers to the 7-inch Tape and Reel packaging format.