SLUS964D NOVEMBER   2009  – March 2018 TPS40303 , TPS40304 , TPS40305

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Application Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 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 Voltage Reference
      2. 7.3.2 Enable Functionality, Start-Up Sequence and Timing
      3. 7.3.3 Soft-Start Time
      4. 7.3.4 Oscillator and Frequency Spread Spectrum (FSS)
      5. 7.3.5 Overcurrent Protection
      6. 7.3.6 Drivers
      7. 7.3.7 Prebias Start-Up
      8. 7.3.8 Power Good
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
        1. 7.4.1.1 UVLO
        2. 7.4.1.2 Disable
        3. 7.4.1.3 Calibration
        4. 7.4.1.4 Converting
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Using the TPS40305 for a 12-V to 1.8-V Point-of-Load Synchronous Buck Regulator
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2  Selecting the Switching Frequency
          3. 8.2.1.2.3  Inductor Selection (L1)
          4. 8.2.1.2.4  Output Capacitor Selection (C12)
          5. 8.2.1.2.5  Peak Current Rating of Inductor
          6. 8.2.1.2.6  Input Capacitor Selection (C8)
          7. 8.2.1.2.7  MOSFET Switch Selection (Q1 and Q2)
          8. 8.2.1.2.8  Bootstrap Capacitor (C6)
          9. 8.2.1.2.9  VDD Bypass Capacitor (C7)
          10. 8.2.1.2.10 BP Bypass Capacitor (C5)
          11. 8.2.1.2.11 Short-Circuit Protection (R11)
          12. 8.2.1.2.12 Feedback Divider (R4, R5)
          13. 8.2.1.2.13 Compensation: (C2, C3, C4, R3, R6)
        3. 8.2.1.3 Application Curves
      2. 8.2.2 A High-Current, Low-Voltage Design Using the TPS40304
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1  Selecting the Switching Frequency
          2. 8.2.2.2.2  Inductor Selection (L1)
          3. 8.2.2.2.3  Output Capacitor Selection (C12)
          4. 8.2.2.2.4  Peak Current Rating of Inductor
          5. 8.2.2.2.5  Input Capacitor Selection (C8)
          6. 8.2.2.2.6  MOSFET Switch Selection (Q1 and Q2)
          7. 8.2.2.2.7  Bootstrap Capacitor (C6)
          8. 8.2.2.2.8  VDD Bypass Capacitor (C7)
          9. 8.2.2.2.9  BP Bypass Capacitor (C5)
          10. 8.2.2.2.10 Short-Circuit Protection (R11)
          11. 8.2.2.2.11 Feedback Divider (R4, R5)
          12. 8.2.2.2.12 Compensation: (C2, C3, C4, R3, R6)
        3. 8.2.2.3 Application Curves
      3. 8.2.3 A Synchronous Buck Application Using the TPS40303
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
          1. 8.2.3.2.1  Selecting the Switching Frequency
          2. 8.2.3.2.2  Inductor Selection (L1)
          3. 8.2.3.2.3  Output Capacitor Selection (C12)
          4. 8.2.3.2.4  Peak Current Rating of Inductor
          5. 8.2.3.2.5  Input Capacitor Selection (C8)
          6. 8.2.3.2.6  MOSFET Switch Selection (Q1 and Q2)
          7. 8.2.3.2.7  Bootstrap Capacitor (C6)
          8. 8.2.3.2.8  VDD Bypass Capacitor (C7)
          9. 8.2.3.2.9  BP Bypass Capacitor (C5)
          10. 8.2.3.2.10 Short-Circuit Protection (R11)
          11. 8.2.3.2.11 Feedback Divider (R4, R5)
          12. 8.2.3.2.12 Compensation: (C2, C3, C4, R3, R6)
        3. 8.2.3.3 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 Third-Party Products Disclaimer
    2. 11.2 Custom Design With WEBENCH® Tools
    3. 11.3 Documentation Support
      1. 11.3.1 Related Documentation
    4. 11.4 Related Links
    5. 11.5 Receiving Notification of Documentation Updates
    6. 11.6 Community Resources
    7. 11.7 Trademarks
    8. 11.8 Electrostatic Discharge Caution
    9. 11.9 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

8.2.1.1 Design Requirements

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

Table 1. Design Example Electrical Characteristics

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIN Input voltage 8 14 V
VIN(ripple) Input ripple IOUT = 10 A 0.6 V
VOUT Output voltage 0 A ≤ IOUT ≤ 10 A 1.764 1.800 1.836 V
Line regulation 8 V ≤ VIN ≤ 14 V 0.5%
Load regulation 0 A ≤ IOUT ≤ 10 A 0.5%
VRIPPLE Output ripple IOUT = 10 A 36 mV
VOVER Output overshoot IOUT falling from 7 A to 3 A 100 mV
VUNDER Output undershoot IOUT rising from 3 A to 7 A 100 mV
IOUT Output current 4.5 V ≤ VIN ≤ 5.5 V 0 10 A
tSS Soft-start time VIN = 12 V 1.5 ms
ISCP Short-circuit current trip point 13 15 A
fSW Switching frequency 1200 kHz
Size 1 in2

The bill of materials for this application is shown in Table 2. The efficiency, line, and load regulation from boards built using this design are shown in Figure 14. Gerber files and additional application information are available from the factory.

Table 2. Design Example List of Materials

REFERENCE
DESIGNATOR		 QTY VALUE DESCRIPTION SIZE PART NUMBER MFR
C1 1 3.3 nF Capacitor, Ceramic, 10 V, X7R, 20% 0603 Std Std
C2 1 820 pF Capacitor, Ceramic, 25 V, X7R, 10% 0603 Std Std
C3 1 150 pF Capacitor, Ceramic, 25 V, X7R, 10% 0603 Std Std
C4 1 3300 pF Capacitor, Ceramic, 25 V, X7R, 10% 0603 Std Std
C5 1 1.0 µF Capacitor, Ceramic, 10 V, X7R, 20% 0805 Std Std
C6 1 100 nF Capacitor, Ceramic, 16 V, X7R, 20% 0603 Std Std
C7 1 1 µF Capacitor, Ceramic, 25 V, X7R, 20% 0805 Std Std
C8 2 10 µf Capacitor, Ceramic, 25 V, X7R, 10% 1210 Std Std
C11 1 330 µF Capacitor, Aluminum, 25 V, ±20%, 160 mΩ 0.328 × 0.390 inch EEVFK1E331P Panasonic
C12 2 22 µF Capacitor, Ceramic, 6.3 V, X5R, 20% 0805 Std Std
L1 1 0.32 µH Inductor, SMT, 17 A 0.268 × 0.268 inch PG0083.401 Pulse
Q1 1 MOSFET, N-Channel, 25 V, 97 A, 4.6 mΩ QFN-8 POWER CSD16322Q5 TI
Q2 1 MOSFET, N-Channel, 25 V, 59 A, 9.6 mΩ QFN-8 POWER CSD16410Q5A TI
R3 1 422 Ω Resistor, Chip, 1/16W, 1% 0603 Std Std
R4 1 10.0 kΩ Resistor, Chip, 1/16W, 1% 0603 Std Std
R5 1 4.99 kΩ Resistor, Chip, 1/16W, 1% 0603 Std Std
R6 1 2.20 kΩ Resistor, Chip, 1/16W, 1% 0603 Std Std
R8 1 100 kΩ Resistor, Chip, 1/16W, 1% 0603 Std Std
R10 1 2 Ω Resistor, Chip, 1/16W, 1% 0603 Std Std
R11 1 3.74 kΩ Resistor, Chip, 1/16W, 1% 0603 Std Std
U1 1 IC, 3-V to 20-V sync. 1.2-MHz Buck controller DRC10 TPS40305DRC TI