The **LL431NSG-AE2-R** is a specific part number for a programmable precision shunt regulator. It is widely used in power management circuits to provide a stable reference voltage. --- ### 1. General Specifications The device acts like a Zener diode with a programmable output voltage, which is set using two external resistors. | Parameter | Details | | :--- | :--- | | **Device Type** | Adjustable Precision Shunt Regulator | | **Reference Voltage ($V_{ref}$)** | Typically 2.495V (Standard) | | **Output Voltage Range** | $V_{ref}$ to 36V | | **Sink Current Capability** | 1.0mA to 100mA | | **Package Type** | SOT-23 (Common for AE2 suffix) | | **Temperature Stability** | Low temperature coefficient (typical 50 ppm/°C) | --- ### 2. Part Number Breakdown The nomenclature usually follows the standards of manufacturers like **UTC (Unisonic Technologies)**: * **LL431**: The base series (Equivalent to the industry-standard TL431). * **NS**: Low noise or specific voltage tolerance characteristic. * **G**: Halogen-free and RoHS compliant (Green). * **AE2**: Package code, typically designating **SOT-23**. * **R**: Tape and Reel packaging. --- ### 3. Pin Configuration For the SOT-23 package (AE2), the pinout is generally as follows: | Pin Number | Function | Description | | :--- | :--- | :--- | | 1 | **Reference (REF)** | Used to set the output voltage via a divider. | | 2 | **Cathode (K)** | The positive terminal of the regulator. | | 3 | **Anode (A)** | The ground/negative terminal. | --- ### 4. Typical Application Circuit To calculate the output voltage ($V_{out}$), the following formula is used (ignoring the small reference input current): ```markdown Vout = Vref * (1 + R1 / R2) ``` **Common Uses:** * **Switch Mode Power Supplies (SMPS):** Used in the feedback loop (often with an optocoupler). * **Voltage Monitoring:** Acting as a comparator with a precise threshold. * **Constant Current Sources:** Combined with a transistor to regulate current. --- ### 5. Key Features * **High Precision:** Offers tight tolerance on the reference voltage (often 0.5% or 1%). * **Fast Turn-on Response:** Makes it ideal for high-speed switching regulators. * **Low Output Noise:** Ensures stability in sensitive analog circuits.