SBVS256A May   2016  – September 2016 TPS7A19

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 Timing Requirements
    7. 6.7 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 Enable Pin (EN)
      2. 7.3.2 Regulated Output Pin (OUT)
      3. 7.3.3 Power-Good Pin (PG)
      4. 7.3.4 Delay Timer Pin (DELAY)
      5. 7.3.5 Adjustable Output Voltage (ADJ for TPS7A1901)
      6. 7.3.6 Undervoltage Shutdown
      7. 7.3.7 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With VIN < 4 V
      2. 7.4.2 Operation With EN Control
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Power Dissipation and Thermal Considerations
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Evaluation Modules
        2. 11.1.1.2 Spice Models
      2. 11.1.2 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8 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.

8.1 Application Information

Figure 13 shows a typical application circuit for the TPS7A1901. Based on the end-application, different values of external components can be used. Some applications may require a larger output capacitor during fast load steps in order to prevent a PG low from occurring. Use a low-ESR ceramic capacitor with a dielectric of type X5R or X7R for better load transient response.

8.2 Typical Application

TPS7A19 SBVS256_adjapp.gif Figure 13. Adjustable Operation

8.2.1 Design Requirements

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

Table 1. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
Input voltage 12 V, ±10%
Output voltage 3.3 V
Output current 50 mA (max)
PG delay time 1 ms

8.2.2 Detailed Design Procedure

To begin the design process:

  1. First, make sure that the combination of maximum current, maximum ambient temperature, maximum input voltage, and minimum output voltage does not exceed the maximum operating condition of TJ = 125°C. The Power Dissipation and Thermal Considerations section describes how to calculate the maximum ambient temperature and power dissipation.
  2. Next, set the feedback resistors to give the desired output voltage. See Equation 2 for the VOUT relationship to R1 and R2. A good nominal value for R2 is 10 kΩ.
  3. Then, calculate the required CDELAY capacitor to achieve the desired PG delay time using Equation 1. For 1 ms of delay, the nearest standard value capacitor is 10 nF.
  4. Finally, select an output capacitor with a total effective capacitance between 22 µF and 500 µF, a sufficient voltage rating, and an ESR below 20 Ω. Higher capacitance gives improved transient response, but results in higher inrush current at startup.

8.2.2.1 Power Dissipation and Thermal Considerations

Device power dissipation is calculated with Equation 3.

Equation 3. TPS7A19 eq_3_dissipation_sbvs256.gif

where

  • PD = continuous power dissipation
  • IOUT = output current
  • VIN = input voltage
  • VOUT = output voltage

As IQ « IOUT, the term IQ × VIN in Equation 3 can be ignored.

For a device under operation at a given ambient air temperature (TA), calculate the junction temperature (TJ) with Equation 4.

Equation 4. TPS7A19 eq_4_tj_sbvs256.gif

where

  • θJA = junction-to-ambient air thermal impedance

A rise in junction temperature because of power dissipation can be calculated with Equation 5.

Equation 5. TPS7A19 eq_5_delta_tj_sbvs256.gif

For a given maximum junction temperature (TJM), the maximum ambient air temperature (TAM) at which the device can operate is calculated with Equation 6.

Equation 6. TPS7A19 eq_6_max_ta_sbvs256.gif

8.2.3 Application Curves

TPS7A19 enable_startup_sbvs256.gif
VIN = 12 V, VEN step from 0 V to 12 V, CIN = 10 µF,
COUT = 22 µF, RLOAD = 66 Ω
Figure 14. Enable Startup
TPS7A19 enable_shutdown_sbvs256.gif
VIN = 12 V, VEN step from 12 V to 0 V, CIN = 10 µF,
COUT = 22 µF, RLOAD = 66 Ω
Figure 15. Enable Shutdown