SBVS393B December   2020  – November 2022 TPS7A43

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 MID_OUT Voltage Selection
      2. 7.3.2 Precision Enable
      3. 7.3.3 Dropout Voltage
      4. 7.3.4 Current Limit
      5. 7.3.5 Thermal Shutdown
      6. 7.3.6 Power Good
    4. 7.4 Device Functional Modes
      1. 7.4.1 Device Functional Mode Comparison
      2. 7.4.2 Normal Operation
      3. 7.4.3 Dropout Operation
      4. 7.4.4 Disabled
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 MID_OUT Voltage Setting
      2. 8.1.2 Adjustable Device Feedback Resistors
      3. 8.1.3 Recommended Capacitor Types
      4. 8.1.4 Input and Output Capacitor Requirements
      5. 8.1.5 Power Dissipation (PD)
      6. 8.1.6 Estimating Junction Temperature
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Examples
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
        1. 9.1.1.1 Evaluation Modules
        2. 9.1.1.2 Spice Models
      2. 9.1.2 Device Nomenclature
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

7.4.3 Dropout Operation

Because the TPS7A43 has two output rails (MID_OUT and OUT), the device can be in either VDO(MID_OUT) or VDO(OUT), or in both depending on the input voltage level while all other conditions are met for normal operation. When the input voltage drops to lower than VMID_OUT(nom) + VDO(MID_OUT), the device is in VDO(MID_OUT) dropout. During this rail dropout, VMID_OUT tracks VIN and the transient performance of VMID_OUT becomes significantly degraded because the pass transistor is in the ohmic or triode region, and acts as a switch. The MID_OUT rail line or load transients in the VDO(MID_OUT) dropout can result in large VMID_OUT deviations. When the device is still in VDO(MID_OUT) and when VIN is higher than VOUT(nom) + VDO(OUT), VOUT is in regulation and is not in VDO(OUT) dropout. When VIN drops below VOUT(nom) + VDO(OUT), VOUT is no longer in regulation and transient performance becomes significantly degraded.

When the device is in a steady dropout state (when the device is in both VDO(MID_OUT) and VDO(OUT) dropout, directly after being in a normal regulation state, but not during start up), the pass transistor is driven into the ohmic or triode region. When the input voltage returns to a value greater than or equal to VMID_OUT(nom) + VDO(MID_OUT) and greater than VOUT(NOM) + VDO, the output voltage (OUT) can overshoot for a short period of time while the device pulls the pass transistor back into the linear region.