The **81N48L-R-AB3-I-R** is a specific part number for a **Voltage Detector IC** manufactured by **UTC (Unisonic Technologies Co., Ltd)**. It is primarily used to monitor power supply levels and reset microprocessors when the voltage drops below a specific threshold. ### 1. Part Number Breakdown The nomenclature for this UTC part provides specific details about its functionality: | Segment | Meaning | Detail | | :--- | :--- | :--- | | **81N** | Series | Low Power Consumption Voltage Detector | | **48** | Detection Voltage | **4.8V** (Threshold level) | | **L** | Lead Plating | Halogen Free / Lead Free | | **-R** | Output Type | **Reset High** (Open Drain) | | **-AB3** | Package Type | **SOT-89** package | | **-I** | Temperature Grade | Industrial Grade | | **-R** | Packing | Tape & Reel | --- ### 2. Technical Specifications This component is designed for high accuracy and low power consumption. * **Detection Voltage ($V_{DET}$):** 4.8V (Fixed). * **Hysteresis Voltage:** Typically 5% of $V_{DET}$ (preventing "chatter" or rapid switching). * **Supply Voltage ($V_{DD}$):** 1.0V to 15.0V. * **Current Consumption:** Low, typically around $1\mu A$ to $3\mu A$ (ideal for battery devices). * **Output Type:** N-channel open drain. --- ### 3. Key Features and Applications #### Features: - **High Accuracy:** Usually ±2% detection voltage accuracy. - **Low Power:** Essential for mobile or standby-heavy electronics. - **Wide Operating Voltage:** Can monitor a variety of logic levels. #### Common Applications: 1. **Microprocessor Reset:** Generates a reset signal when power is unstable to prevent data corruption. 2. **Battery Level Monitoring:** Signals a "Low Battery" warning when the cell voltage reaches 4.8V. 3. **Power Failure Detection:** Acts as a safety switch to shut down sensitive components during a brownout. --- ### 4. Basic Application Circuit Since this is an **N-Channel Open Drain** output, it typically requires a pull-up resistor to the supply line ($V_{CC}$). ```c V_in (Monitor) ----+----[ 81N48L ] | | | | GND OUT ----> To MCU Reset Pin | | +--[Resistor]-- V_pullup ``` ---