## ADM1818-R23ART-RL7: Microprocessor Reset Circuit The **ADM1818-R23ART-RL7** is a low-power, precision voltage monitoring device manufactured by Analog Devices. It is designed to monitor power supply voltages in microprocessor systems and provide a reset signal to the processor when the voltage falls below a predefined threshold. --- ### 1. Key Technical Specifications | Parameter | Specification | | :--- | :--- | | **Threshold Voltage ($V_{TH}$)** | 2.31V (Nominal) | | **Supply Voltage Range** | 1.0V to 5.5V | | **Supply Current** | 4 $\mu$A (Typical) | | **Reset Timeout Period** | 150 ms (Minimum) | | **Output Type** | Open-Drain (Active Low) | | **Package / Case** | SOT-23-3 | | **Operating Temperature** | -40°C to +85°C | --- ### 2. Part Number Breakdown Understanding the suffix is critical for identifying the specific behavior of this component: * **ADM1818**: The base series (Microprocessor Reset Circuit). * **R23**: Represents the reset threshold voltage. In this case, it is calibrated for **2.31V**, typically used for monitoring **2.5V** power rails. * **ART**: Refers to the package type (**SOT-23**). * **RL7**: Indicates the packaging format (7-inch Reel, Tape & Reel). --- ### 3. Functional Features #### Reset Logic The device features an **Active Low** reset. When the monitored $V_{CC}$ drops below the 2.31V threshold, the `/RESET` pin goes Low. It stays Low for a "timeout period" (approx. 150ms) after the voltage rises back above the threshold to ensure the system clock has stabilized. #### Open-Drain Output Because the output is open-drain, it requires an external **pull-up resistor** connected to a voltage source (usually the $V_{CC}$ of the microprocessor). This allows for "wired-OR" connections if multiple reset sources are needed. #### Debounced Manual Reset The `/RESET` pin can also be used as a manual reset input. If the pin is pulled low by an external switch, the device will trigger a reset cycle once the switch is released. --- ### 4. Typical Application Circuit In a standard configuration, the ADM1818 is placed between the power supply and the Microcontroller (MCU). ```text [+2.5V Rail] | +-----+-----+ | Vcc | [Pull-up Resistor] | | | | ADM1818 | /RESET --------+------> [MCU RESET Pin] | | | GND | +-----+-----+ | [GND] ``` ---