The **TL432L-AE3-R** is a low-voltage three-terminal adjustable shunt regulator. It is widely used in power management circuits as a precision voltage reference. It is functionally similar to the industry-standard TL431 but optimized for lower output voltages and specific packaging. --- ### 1. Key Technical Specifications The "L" in the part number typically signifies a low-voltage version, allowing it to regulate down to 1.24V rather than the standard 2.5V of a traditional TL431. | Feature | Specification | | :--- | :--- | | **Reference Voltage ($V_{ref}$)** | 1.24V (typical) | | **Output Voltage Range** | $V_{ref}$ to 18V | | **Cathode Current Range** | 80µA to 100mA | | **Dynamic Impedance** | 0.25Ω (typical) | | **Operating Temperature** | -40°C to +85°C | | **Package Type** | SOT-23 (AE3 designation) | --- ### 2. Pin Configuration (SOT-23) The **AE3** suffix refers to the SOT-23 package. The pinout is critical for PCB design: 1. **Reference (REF):** Input voltage that is compared to the internal 1.24V bandgap reference. 2. **Cathode (K):** The output terminal (acts like the collector of an NPN transistor). 3. **Anode (A):** The common/ground terminal. --- ### 3. Functional Description The TL432 behaves like a Zener diode with a programmable breakdown voltage. When the voltage at the **REF** pin exceeds 1.24V, the device begins to conduct current from the **Cathode** to the **Anode**. #### Mathematical Formula for Output Voltage: In a typical shunt regulator configuration using two resistors ($R1$ and $R2$), the output voltage ($V_{out}$) is calculated as: $$V_{out} = V_{ref} \times \left(1 + \frac{R1}{R2}\right)$$ --- ### 4. Common Applications * **Linear Regulators:** Used as a reference for adjustable power supplies. * **Switching Power Supplies (SMPS):** Used in the feedback loop (often paired with an optocoupler) to provide isolated regulation. * **Voltage Monitoring:** Acting as a comparator to trigger over-voltage or under-voltage protection. * **Constant Current Sources:** By placing a precision resistor in the feedback path. --- ### 5. Part Number Breakdown * **TL432:** Low-voltage adjustable shunt regulator (1.24V ref). * **L:** Refers to the low voltage/low current characteristic. * **AE3:** SOT-23 Package. * **R:** Tape & Reel (Packaging method).