The **81N13L-R-AB3-I-R** is a specific part number for a **Voltage Detector IC** manufactured by **UTC (Unisonic Technologies Co., Ltd)**. These components are primarily used to monitor power supply rails and provide a reset signal if the voltage drops below a specific threshold. --- ### 1. Part Number Breakdown The alphanumeric string follows a specific nomenclature used by UTC to define the technical characteristics: | Code Segment | Meaning | Specification | | :--- | :--- | :--- | | **81N** | Series Name | Low power consumption voltage detector | | **13** | Detect Voltage | **1.3V** threshold level | | **L** | Lead Plating | Lead-free and Halogen-free (RoHS) | | **R** | Output Type | **Reset** active low (Open Drain) | | **AB3** | Package Type | **SOT-89** package | | **I** | Pin Assignment | Specific pin configuration layout | | **R** | Packing | **Tape & Reel** | --- ### 2. Technical Specifications Based on the datasheet for the UTC 81N series, here are the key electrical parameters: * **Detection Voltage ($V_{DET}$):** 1.3V ($\pm 2\%$ accuracy). * **Hysteresis Voltage:** Typically $V_{DET} \times 0.05$. * **Current Consumption:** Very low, typically **1.0 $\mu$A** to **3.0 $\mu$A**. * **Operating Voltage Range:** 0.7V to 10V (depending on specific conditions). * **Output Type:** N-Channel Open Drain. This means you usually need an external pull-up resistor. --- ### 3. Functional Blocks The internal circuitry of this IC consists of four main components: 1. **Reference Voltage Source:** Provides a stable voltage to compare against. 2. **Comparator:** Compares the input voltage to the reference. 3. **Hysteresis Circuit:** Prevents "chattering" or rapid switching near the threshold. 4. **Output Driver:** An N-MOS transistor that pulls the output pin to Ground when the voltage is low. --- ### 4. Common Applications This part is commonly found in battery-powered devices and microprocessor systems to ensure reliable operation: * **Microprocessor Reset:** Holding a CPU in reset mode until the power supply stabilizes. * **Battery Life Monitoring:** Signaling when a battery has reached a critically low level. * **Level Discriminators:** Simple circuits that trigger an action at a specific voltage level. --- ### 5. Typical Application Circuit To use this device, a pull-up resistor is required because it is an Open-Drain output. ```markdown Vcc (Input) | +-------[ Pull-up Resistor ]-------+ | | [ 81N13L ] Pin 2 (VDD) Pin 1 (Vout/Reset) ----> To MCU Reset Pin [ ] Pin 3 (VSS/GND) | GND ``` ---