The **81N11L-R-AB3-I-R** is a specific part number for a precision voltage detector (Reset IC) manufactured by **UTC (Unisonic Technologies Co., Ltd)**. It is primarily used to monitor power supply levels and trigger a system reset if the voltage drops below a certain threshold. --- ### 1. Technical Specifications | Parameter | Details | | :--- | :--- | | **Detection Voltage** | 1.1V (Fixed) | | **Output Type** | N-Channel Open Drain | | **Package Type** | SOT-89 | | **Voltage Accuracy** | ±2.0% | | **Operating Voltage Range** | 0.7V to 10V | | **Quiescent Current** | Very Low (approx. 1.0µA to 3.0µA) | | **Operating Temperature** | -40°C to +85°C | --- ### 2. Part Number Breakdown Understanding the suffix codes is essential for sourcing the correct component: * **81**: Series code for Voltage Detectors. * **N**: Output configuration (N-Channel Open Drain). * **11**: Detection Voltage (1.1V). * **L**: Lead-free/Halogen-free plating. * **R**: Taping/Reel packaging. * **AB3**: Package code for **SOT-89**. * **I**: Industrial temperature grade. --- ### 3. Functional Description This device acts as a "watchdog" for the power supply. Its operation follows this logic: 1. **Monitoring**: It continuously checks the input voltage ($V_{DD}$). 2. **Triggering**: If $V_{DD}$ falls below the detection threshold (1.1V), the output pin ($V_{OUT}$) goes **Low** (Logic 0). 3. **Reset Release**: Once the voltage rises above the threshold (plus a small amount of hysteresis), the output returns to a **High-Z** (high impedance) state, allowing an external pull-up resistor to pull the signal High. --- ### 4. Typical Application Circuit Because this is an **Open Drain** output, a pull-up resistor is mandatory for proper operation. ```mermaid [Power Source VDD] | +-------+-----------+ | | | [In] [Resistor] | 81N11L | [Microcontroller] [Out]----+------> [Reset Pin] | [GND] ``` --- ### 5. Key Applications * Microprocessor reset circuitry. * Battery-powered equipment (low power consumption is critical). * Battery life monitors. * Power failure detection in industrial systems.