Overview
The LM431AIM3X/NOPB is an adjustable precision shunt voltage regulator manufactured by Texas Instruments. This device is known for its temperature stability across the entire operating temperature range, making it suitable for a variety of applications. The LM431 is available in several package types, including SOIC-8, SOT-23, and TO-92, which cater to space-critical designs. It operates as a precision Zener diode, requiring a small quiescent current for regulation and adjusting the output voltage by shunting current to ground based on input voltage and load conditions.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Output Voltage Range | 2.5 | - | 37 | V |
| Minimum Operating Current | 1 | - | - | mA |
| Maximum Operating Current | - | - | 100 | mA |
| Reference Voltage (VREF) | - | 2.5 | - | V |
| Dynamic Output Impedance (rZ) | - | 0.5 | - | Ω |
| Temperature Range | - | - | - | 0°C to 70°C |
| ESD Rating (Human-body model) | - | - | ±2500 | V |
Key Features
- Adjustable Output Voltage: The output voltage can be adjusted to any value between 2.5 V and 37 V using external feedback resistors.
- Temperature Stability: Ensured temperature stability over the entire operating temperature range.
- Low Quiescent Current: Requires a small quiescent current for regulation.
- Compact Packages: Available in SOIC-8, SOT-23, and TO-92 packages to meet space-critical requirements.
- ESD Protection: Limited built-in ESD protection, with a rating of ±2500 V (Human-body model).
Applications
- Shunt Voltage Regulation: Commonly used in shunt regulator applications to regulate voltage by shunting excess current to ground.
- Zener Diode Replacement: Excellent replacement for many Zener diode applications due to its sharp turn-on characteristics.
- Space-Critical Designs: Suitable for applications where space is limited due to its compact package options.
- General Voltage Regulation: Used in various voltage regulation circuits where precision and temperature stability are required.
Q & A
- What is the output voltage range of the LM431?
The output voltage range of the LM431 is from 2.5 V to 37 V.
- What are the minimum and maximum operating currents for the LM431?
The minimum operating current is 1 mA, and the maximum operating current is 100 mA.
- What is the reference voltage (VREF) of the LM431?
The reference voltage (VREF) of the LM431 is typically 2.5 V.
- What is the dynamic output impedance (rZ) of the LM431?
The dynamic output impedance (rZ) of the LM431 is typically 0.5 Ω.
- What are the package options available for the LM431?
The LM431 is available in SOIC-8, SOT-23, and TO-92 packages.
- What is the ESD rating of the LM431?
The ESD rating of the LM431 is ±2500 V (Human-body model).
- How do you set the output voltage of the LM431?
The output voltage of the LM431 can be set using external feedback resistors (R1 and R2) based on the internal reference voltage (VREF).
- Is an external capacitor required for the LM431?
An external capacitor is not required but can be used to reduce noise on the input voltage line.
- What are the key considerations for selecting the series resistor (RS) in a shunt regulator application?
The series resistor (RS) must be selected to ensure the current through the LM431 remains between 1 mA and 100 mA across the entire supply voltage and load range.
- What is thermal hysteresis in the context of the LM431?
Thermal hysteresis refers to the change in output voltage measured at 25°C after thermal cycling between 0°C and 70°C, caused by thermal-mechanical package stress.
