SLVSCV5E March   2015  – December 2024 ATL431 , ATL432

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics, ATL431Ax, ATL432Ax
    6. 5.6 Electrical Characteristics, ATL431Bx, ATL432Bx
    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 Application 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 Curve
      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 Curves
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

Package Options

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

7.3 Feature Description

ATL43x consists of an internal reference and amplifier that outputs a sink current based 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 (≥ 2.5V) and cathode current (IKA), ATL43x forces the reference pin to 2.5V. However, the reference pin can not be left floating, as it needs Iref ≥ 0.1µA (please see the Functional Block Diagram). 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, ATL43x 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 required in the above feedback situation must be applied to this device in open-loop, servo, or error amplifying implementations for the current to be in the proper linear region to give the ATL43x enough gain.

Unlike many linear regulators, ATL43x 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 5-14 through Figure 5-21 can be used as a guide to assist in choosing the correct capacitor to maintain stability.