SLVS887C April   2009  â€“ August 2014 TPS53114

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Schematics
  5. 5 Revision History
  6. 6 Pin Configurations and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Handling Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 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  PWM Operation
      2. 8.3.2  Drivers
      3. 8.3.3  PWM Frequency and Adaptive On-time Control
      4. 8.3.4  5-Volt Regulator
      5. 8.3.5  Soft Start
      6. 8.3.6  Pre-bias Support
      7. 8.3.7  Switching Frequency Selection
      8. 8.3.8  Output Discharge Control
      9. 8.3.9  Over Current Protection
      10. 8.3.10 Over/under Voltage Protection
      11. 8.3.11 UVLO Protection
      12. 8.3.12 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 350-kHz Operation Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Choose Inductor
        2. 9.2.2.2 Choose Output Capacitor
        3. 9.2.2.3 Choose Input Capacitor
        4. 9.2.2.4 Choose Bootstrap Capacitor
        5. 9.2.2.5 Choose VREG5 and V5FILT Capacitors
        6. 9.2.2.6 Choose Output Voltage Set Point Resistors
        7. 9.2.2.7 Choose Over Current Set Point Resistor From: IOCL + To: IOCL - minus VOCLoff
        8. 9.2.2.8 Choose Soft Start Capacitor
        9. 9.2.2.9 Choose Package Option
      3. 9.2.3 350 kHz Application Curves
    3. 9.3 700 kHz Operation Application
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
      3. 9.3.3 700 kHz Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9 Application and Implementation

9.1 Application Information

9.2 350-kHz Operation Application

The schematic of Figure 12 shows a typical 350-kHz application schematic. The 350 kHz switching frequency is selected by connecting FSEL to the GND pin. The input voltage is 12 V and the output voltage is 1.05 V.

typapp1_lvs887.gifFigure 12. Typical Application Circuit at 350-kHz Switching Frequency Selection (FSEL pin = GND)

9.2.1 Design Requirements

Table 1. Design Parameters

PARAMETERS EXAMPLE VALUES
Input voltage 12 V
Output voltage 1.05 V
Output current 4 A
Switching frequency 350 kHz

9.2.2 Detailed Design Procedure

9.2.2.1 Choose Inductor

The inductance value is selected to provide approximately 30% peak to peak ripple current at maximum load. Larger ripple current increases output ripple voltage, improve S/N ratio and contribute to stable operation. L1 can be calculated using Equation 3.

Equation 3. eq3_lvs887.gif

The inductors current ratings needs to support both the RMS (thermal) current and the peak (saturation) current. The RMS and peak inductor current can be estimated as follows:

Equation 4. eq4_lvs887.gif
Equation 5. eq5_lvs887.gif
Equation 6. eq6_lvs887.gif

Note:

The calculation above shall serve as a general reference. To further improve transient response, the output inductance could be reduced further. This needs to be considered along with the selection of the output capacitor.

9.2.2.2 Choose Output Capacitor

The capacitor value and ESR determines the amount of output voltage ripple and load transient response. Recommend to use ceramic output capacitor.

Equation 7. eq7_lvs887.gif
Equation 8. eq8_lvs887.gif

Where:

Equation 9. eq9_lvs887.gif
Equation 10. eq10_lvs887.gif

Select the capacitance value greater than the largest value calculated from Equation 7, Equation 8 and Equation 10. The capacitance for C1 should be greater than 66 μF.

Where:

Δ VOS = The allowable amount of overshoot voltage in load transition

ΔVUS = The allowable amount of undershoot voltage in load transition

Tmin(off) = Minimum off time

9.2.2.3 Choose Input Capacitor

The TPS53114 requires an input decoupling capacitor and a bulk capacitor is needed depending on the application. A minimum 10-μF high-quality ceramic capacitor is recommended for the input capacitor. The capacitor voltage rating needs to be greater than the maximum input voltage.

9.2.2.4 Choose Bootstrap Capacitor

The TPS53114 requires a bootstrap capacitor from SW to VBST to provide the floating supply for the high-side drivers. A minimum 0.1-μF high-quality ceramic capacitor is recommended. The voltage rating should be greater than 10.0 V.

9.2.2.5 Choose VREG5 and V5FILT Capacitors

The TPS53114 requires both the VREG5 regulator and V5FILT input are bypassed. A minimum 4.7-μF high-quality ceramic capacitor must be connected between the VREG5 and GND for proper operation. A minimum 1.0-μF high-quality ceramic capacitor must be connected between the V5FILT and GND for proper operation. Both of these capacitors' voltage ratings should be greater than 10 V.

9.2.2.6 Choose Output Voltage Set Point Resistors

The output voltage is set with a resistor divider from output voltage node to the VFBx pin. It is recommended to use 1% tolerance or better resistors. Select R2 between 10 kΩ and 100 kΩ and use Equation 11 or Equation 12 to calculate R1.

Equation 11. eq11_lvs887.gif
Equation 12. eq12_lvs887.gif

Where:

VFB1(ripple) = Ripple voltage at VFB1

9.2.2.7 Choose Over Current Set Point Resistor

Equation 13. EQ13_vtrip_lvs887.gif
Equation 14. EQ14_Rtrip_lvs887.gif

Where:

RDS(ON) = Low side FET on-resistance

ITRIP = TRIP pin source current （≉ 10 μA）

VOCLoff = Minimum over current limit offset voltage (-20 mV)

IOCL = over current limit

9.2.2.8 Choose Soft Start Capacitor

Soft start timing equations are as follows:

Equation 15. eq15_lvs887.gif
Equation 16. eq16_lvs887.gif

9.2.2.9 Choose Package Option

TPS53114 power dissipation:

Equation 17. eq17_lvs887.gif

Where:

CiH = Input capacitor of high side MOSFET

CiL = Input capacitor of low side MOSFET

Choose package considering the Dissipation Rating table.

9.2.3 350 kHz Application Curves

The application curves of Figure 13 and Figure 14 apply to both the circuits of 700 kHz Operation Application and 350-kHz Operation Application.

g008_lvs887.gif
Figure 13. 1.05-V Output Voltage vs. Output Current
g010_lvs887.gif
Figure 15. 1.05-V Load Transient Response
g013_lvs887.gif
Figure 17. 1.05-V Efficiency vs. Output Current
g009_lvs887.gif
Figure 14. 1.05-V Output Voltage vs. Input Voltage
g012_lvs887.gif
Figure 16. Startup Waveform

9.3 700 kHz Operation Application

The schematic of Figure 18 shows a typical 700 kHz application schematic. The 700 kHz switching frequency is selected by connecting FSEL to the V5FILT pin. The input voltage is 12 V and the output voltage is 1.05 V.

typapp2_lvs887.gifFigure 18. Typical Application Circuit at 700-kHz Switching Frequency Selection (FSEL pin = V5FILT)

9.3.1 Design Requirements

Table 2. Design Parameters

PARAMETERS EXAMPLE VALUES
Input voltage 12 V
Output voltage 1.05 V
Output current 4 A
Switching frequency 700 kHz

9.3.2 Detailed Design Procedure

For the Detailed Design Procedure, refer to Detailed Design Procedure.

9.3.3 700 kHz Application Curves

The application curves of Figure 13 and Figure 14 apply to both the circuits of 700 kHz Operation Application and 350-kHz Operation Application.

go11_lvs887.gif
Figure 19. 1.05-V Load Transient Response
g014_lvs887.gif
Figure 21. 1.05-V Efficiency vs. Output Current
g012_lvs887.gif
Figure 20. Startup Waveform