The **TL432CL-AB3-R** is a low-voltage three-terminal adjustable shunt regulator. It is often referred to as a "programmable zener diode" because it can be configured to any voltage between its reference voltage ($V_{ref}$) and its maximum rated voltage using two external resistors. --- ## 1. Technical Specifications The "TL432" series is a lower-voltage, higher-accuracy variant of the classic TL431. | Feature | Specification | | :--- | :--- | | **Reference Voltage ($V_{ref}$)** | 1.24 V (Typical) | | **Output Voltage Range** | $V_{ref}$ to 18 V | | **Sink Current Capability** | 80 $\mu$A to 100 mA | | **Dynamic Impedance** | 0.2 $\Omega$ (Typical) | | **Operating Temperature** | -40°C to +85°C | | **Package Type** | SOT-89 (Represented by "AB3" code) | --- ## 2. Part Number Breakdown Understanding the suffix codes helps identify the specific physical and electrical characteristics: * **TL432**: The base functional model (1.24V Reference). * **C**: Commercial temperature range (0°C to 70°C, though some variants extend to -40°C). * **L**: Lead-free / RoHS Compliant. * **AB3**: Indicates the **SOT-89** package style. * **R**: Tape & Reel packaging for automated assembly. --- ## 3. Internal Functional Block The device consists of an internal voltage reference, an error amplifier, and a shunt transistor. ```mermaid graph LR Ref[Reference 1.24V] --> Comp[-] Input[Ref Pin] --> Comp[+] Comp --> Transistor[Output Transistor] Transistor --> Cathode Anode --> Ground ``` --- ## 4. Key Applications Because the TL432 has a lower reference voltage (1.24V) compared to the TL431 (2.5V), it is ideal for low-voltage power supplies. ### Common Uses: 1. **Shunt Regulator:** Used to provide a stable voltage reference for ADCs or DACs. 2. **Isolated Feedback Loop:** Often used in Switch Mode Power Supplies (SMPS) alongside an optocoupler to regulate output voltage. 3. **Voltage Monitoring:** Used as a comparator in over-voltage or under-voltage detection circuits. 4. **Current Limiter:** Can be configured to limit current in LED drivers. --- ## 5. Basic Circuit Formula To set the output voltage ($V_{out}$), you use a voltage divider between the Cathode, Reference pin, and Anode. **Formula:** $$V_{out} = V_{ref} \times \left(1 + \frac{R1}{R2}\right)$$ *Where $V_{ref}$ is 1.24V.*