SLVS905B December   2008  – July 2024 TLV431A-Q1 , TLV431B-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1.     Pin Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Thermal Information
    4. 5.4 Recommended Operating Conditions
    5. 5.5 Electrical Characteristics for TLV431A-Q1
    6. 5.6 Electrical Characteristics for TLV431B-Q1
    7. 5.7 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Open Loop (Comparator)
      2. 7.4.2 Closed Loop
  9. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Comparator with Integrated Reference (Open Loop)
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Basic Operation
          2. 8.2.1.2.2 Overdrive
          3. 8.2.1.2.3 Output Voltage and Logic Input Level
            1. 8.2.1.2.3.1 Input Resistance
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Shunt Regulator/Reference
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Programming Output/Cathode Voltage
          2. 8.2.2.2.2 Total Accuracy
          3. 8.2.2.2.3 Stability
        3. 8.2.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

7.3 Feature Description

TLV431 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 an internal Darlington pair.

When operated with enough voltage headroom (≥ 1.24V) and cathode current (Ika), TLV431 forces the reference pin to 1.24V. However, the reference pin can not be left floating, as it needs Iref ≥ 0.5µA (please see the Section 7.2). 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, TLV431 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 it to be in the proper linear region giving TLV431 enough gain.

Unlike many linear regulators, TLV431 is internally compensated to be stable without an output capacitor between the cathode and anode. However, if it is desired to use an output capacitor Figure 5-18 can be used as a guide to assist in choosing the correct capacitor to maintain stability.