SLVSCJ8B November   2014  – January 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Typical Application Schematic
  5. 5 Revision History
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input (IN)
      2. 8.3.2 Output (OUT)
      3. 8.3.3 Output Capacitor Selection
      4. 8.3.4 Low-Voltage Tracking
      5. 8.3.5 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operation With VI Less Than 4 V
      2. 8.4.2 Operation With VI Greater Than 4 V
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Input Capacitor
        2. 9.2.2.2 Output Capacitor
        3. 9.2.2.3 Power Dissipation and Thermal Considerations
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Related Links
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

9 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

9.1 Application Information

The TPS7B69xx-Q1 family of devices is a 150-mA low-dropout linear regulator designed for up to 40-V VI operation with only 15-µA quiescent current at light loads. Use the PSpice transient model to evaluate the base function of the device. To download the PSpice transient model, go to the device product folder on www.TI.com. In addition to this model, specific evaluation modules (EVM) are available for these devices. For the EVM and the EVM user guide, go to the device product folder.

9.2 Typical Application

Figure 25 shows the typical application circuit for the TPS7B69xx-Q1 family of devices. Based on the end-application, different values of external components can be used. An application can require a larger output capacitor during fast load steps to achieve better load transient response. TI recommends a low-ESR ceramic capacitor with a dielectric of type X5R or X7R for better load transient response.

alt_slvscj8.gifFigure 25. Typical Application Schematic for TPS7B69xx-Q1

9.2.1 Design Requirements

For this design example, use the parameters listed in Table 1.

Table 1. Design Parameters

DESIGN PARAMETER EXAMPLE VALUES
Input voltage range 4 to 40 V
Output voltage 2.5 V, 3.3 V, 5 V
Output current rating 150 mA
Output capacitor range 2.2 to 100 µF
Output capacitor ESR range 1 mΩ to 2 Ω

9.2.2 Detailed Design Procedure

To begin the design process, determine the following:

  • Input voltage range
  • Output Voltage
  • Output current rating

9.2.2.1 Input Capacitor

The device requires an input decoupling capacitor, the value of which depends on the application. The typical recommend value for the decoupling capacitor is higher than 0.1 µF. The voltage rating must be greater than the maximum input voltage.

9.2.2.2 Output Capacitor

The device requires an output capacitor to stabilize the output voltage. The output capacitor value should be between 2.2 µF and 100 µF. The ESR value range should be between 1 mΩ and 2 Ω. TI recommends a ceramic capacitor with low ESR to improve the load transient response.

9.2.2.3 Power Dissipation and Thermal Considerations

Use Equation 1 to calculate the power dissipated in the device.

Equation 1. PD = IO × (VI – VO) + IQ × VI

where

  • PD = continuous power dissipation
  • IO = output current
  • VI = input voltage
  • VO = output voltage

Because IQ « IO, the term IQ × VI in Equation 1 can be ignored.

For a device under operation at a given ambient air temperature (TA), use Equation 2 to calculate the junction temperature (TJ).

Equation 2. TJ = TA + (ZθJA × PD)

where

  • ZθJA = junction-to-ambient air thermal impedance

Use Equation 3 to calculate the rise in junction temperature because of power dissipation.

Equation 3. ΔT = TJ – TA = (ZθJA × PD)

For a given maximum junction temperature (TJmax), use Equation 4 to calculate the maximum ambient air temperature (TAmax) at which the device can operate.

Equation 4. TAmax = TJmax – (ZθJA × PD)

9.2.3 Application Curve

waveform_app_slvscj8.gif
CO = 2.2 µF, 400 µs/div
Figure 26. Power Up (5 V)