SNVSCR4 July   2024 TLA431

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Temperature Coefficient
    2. 7.2 Dynamic Impedance
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
      1. 8.4.1 Closed Loop
      2. 8.4.2 Open Loop (Comparator)
  10. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Shunt Regulator/Reference
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Programming Output/Cathode Voltage
          2. 9.2.1.2.2 Total Accuracy
          3. 9.2.1.2.3 Stability
          4. 9.2.1.2.4 Start-Up Time
        3. 9.2.1.3 Application Curve
      2. 9.2.2 Comparator With Integrated Reference
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Basic Operation
            1. 9.2.2.2.1.1 Overdrive
          2. 9.2.2.2.2 Output Voltage and Logic Input Level
            1. 9.2.2.2.2.1 Input Resistance
        3. 9.2.2.3 Application Curve
    3. 9.3 System Examples
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Nomenclature
    2. 10.2 Related Links
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)

8.3 Feature Description

TLA431 consists of an internal reference and amplifier that outputs a sink current base on the difference between the reference pin and the virtual internal pin. The sink current is produced by the internal Darlington pair. A Darlington pair is used for this device to be able to sink a maximum current of 100mA.

When operated with enough voltage headroom (≥ 2.495V) and cathode current (IKA), TLA431 forces the reference pin to 2.495V. However, the reference pin can not be left floating, as the reference pin needs IREF ≥ 4µA (please see Electrical Characteristics). This is because the reference pin is driven into an npn, which needs base current in order operate properly.

When feedback is applied from the Cathode and Reference pins, TLA431 behaves as a Zener diode, regulating to a constant voltage dependent on current being supplied into the cathode. This is due to the internal amplifier and reference entering the proper operating regions. The same amount of current needed in the above feedback situation must be applied to this device in open loop, servo or error amplifying implementations for the TLA431 to be in the proper linear region giving the TLA431 enough gain.

TLA431 is internally compensated to be stable without an output capacitor between the cathode and anode.