SBVS441 December   2022 TPS7B4255

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.     Timing Characteristics
    7. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Regulated Output (VOUT)
      2. 7.3.2 Undervoltage Lockout
      3. 7.3.3 Thermal Protection
      4. 7.3.4 Current Limit
      5. 7.3.5 VOUT Short to Battery
      6. 7.3.6 Tracking Regulator With an Enable Circuit
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With VIN < 3 V
      2. 7.4.2 Operation With ADJ/EN Control
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Dropout Voltage
      2. 8.1.2 Reverse Current
      3. 8.1.3 Signal-Buffering LDO
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input and Output Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Package Mounting
        2. 8.4.1.2 Board Layout Recommendations to Improve PSRR and Noise Performance
        3. 8.4.1.3 Power Dissipation and Thermal Considerations
        4. 8.4.1.4 Thermal Performance Versus Copper Area
      2. 8.4.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Device Nomenclature
      2. 9.1.2 Development Support
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

8.1.3 Signal-Buffering LDO

The TPS7B4255 can be used as a signal buffer up to frequencies of 1 kHz. The output tracks the signal in the ADJ/EN pin if VADJ/EN(min) is greater than VIH. A phase change begins at approximately 2 kHz, causing distortion in the output signal. At frequencies higher than 2 kHz, the signal gets attenuated and distorted further.

Low-dropout regulators (LDOs) cannot sink current into the output, so for the signal-buffering circuit to operate correctly, the device must be loaded. The buffering LDO is limited by the current capability of the device, so use the minimum output capacitor (1 μF) to avoid high AC current.

Figure 8-1 and Figure 8-2 depict the gain and phase, respectively, for the buffering LDO with resistive loads of 62 Ω, 100 Ω, and 330 Ω, and COUT = 1 μF.

Figure 8-1 VADJ/EN Gain vs Frequency
Figure 8-2 VADJ/EN Phase vs Frequency