SLVS346E September   2003  – March 2026 TPS723

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
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagrams
    3. 6.3 Feature Description
      1. 6.3.1 Current Limit
      2. 6.3.2 Enable
      3. 6.3.3 Dropout Voltage
      4. 6.3.4 Output Pullup
      5. 6.3.5 Thermal Shutdown
      6. 6.3.6 Undervoltage Lockout (UVLO)
      7. 6.3.7 NR and Programmable Soft Start
    4. 6.4 Device Functional Modes
      1. 6.4.1 Device Functional Mode Comparison
      2. 6.4.2 Normal Operation
      3. 6.4.3 Dropout Operation
      4. 6.4.4 Disabled
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Adjustable Device Feedback Resistor Selection
      2. 7.1.2 Recommended Capacitor Types
      3. 7.1.3 Input and Output Capacitor Selection
      4. 7.1.4 Reverse Current
      5. 7.1.5 Feed-Forward Capacitor (CFF)
      6. 7.1.6 Power Dissipation (PD)
      7. 7.1.7 Estimating Junction Temperature
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
        1. 7.2.1.1 Capacitor Selection for Stability
        2. 7.2.1.2 Output Noise
        3. 7.2.1.3 Power-Supply Rejection
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 Best Design Practices
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
        1. 8.1.1.1 Spice Models
      2. 8.1.2 Device Nomenclature
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)

6.3.7 NR and Programmable Soft Start

For TPS723, the NR (noise reduction) capacitor in conjunction with the noise-reduction resistor, forms a low-pass filter (LPF) that filters out the noise from the reference before being gained up with the error amplifier, thereby reducing the device noise floor. The LPF is a single-pole filter and the cutoff frequency can be calculated with Equation 2. The typical value of RF is 400kΩ (typical). Increasing the CNR capacitor has a greater affect because the output voltage increases when the noise from the reference is gained up even more at higher output voltages. For low-noise applications, a 10nF (typical) CNR is recommended.

Equation 2. fcutoff = 1(2 × π ×RF×CNR) 

In a new chip version, this NR capacitor (CNR) also helps in controlling the inrush current by introducing RC delay during start-up on the internal reference (VNR). For any external CNR, approximate start-up time, when the internal reference (VNR) charges to the 90% of the typical value can be calculated with Equation 3.

Equation 3. T s t a r t - u p   ≈   2.2   ×   τ   =   2.2   ×   R F ×   C N R  

For more information on current limits, see the How a Noise-reduction Pin Improves System Performance application note.