SLVSFS5A October   2021  – November 2021 TPSM63603

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  System Characteristics
    7. 6.7  Typical Characteristics
    8. 6.8  Typical Characteristics: VIN = 12 V
    9. 6.9  Typical Characteristics: VIN = 24 V
    10. 6.10 Typical Characteristics: VIN = 36 V
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Input Voltage Range
      2. 7.3.2  Adjustable Output Voltage (FB)
      3. 7.3.3  Input Capacitors
      4. 7.3.4  Output Capacitors
      5. 7.3.5  Switching Frequency (RT)
      6. 7.3.6  Output ON/OFF Enable (EN/SYNC) and VIN UVLO
      7. 7.3.7  Frequency Synchronization (EN/SYNC)
      8. 7.3.8  Spread Spectrum
      9. 7.3.9  Power Good Monitor (PG)
      10. 7.3.10 Adjustable Switch-Node Slew Rate (RBOOT/CBOOT)
      11. 7.3.11 Internal LDO, VCC Output, and VLDOIN Input
      12. 7.3.12 Overcurrent Protection (OCP)
      13. 7.3.13 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Active Mode
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design 1: 3-A Synchronous Buck Regulator for Industrial Applications
        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 Output Voltage Setpoint
          3. 8.2.1.2.3 Switching Frequency Selection
          4. 8.2.1.2.4 Input Capacitor Selection
          5. 8.2.1.2.5 Output Capacitor Selection
          6. 8.2.1.2.6 Other Connections
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Design 2: Inverting Buck-Boost Regulator with a –5-V Output
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Output Voltage Setpoint
          2. 8.2.2.2.2 IBB Maximum Output Current
          3. 8.2.2.2.3 Switching Frequency Selection
          4. 8.2.2.2.4 Input Capacitor Selection
          5. 8.2.2.2.5 Output Capacitor Selection
          6. 8.2.2.2.6 Other Connections
        3. 8.2.2.3 Application Curves
        4. 8.2.2.4 EMI
          1. 8.2.2.4.1 EMI Plots
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
      1. 10.2.1 Package Specifications
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support 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

7.3.3 Input Capacitors

Input capacitors are necessary to limit the input ripple voltage to the module due to switching-frequency AC currents. TI recommends using ceramic capacitors to provide low impedance and high RMS current rating over a wide temperature range. Equation 2 gives the input capacitor RMS current. The highest input capacitor RMS current occurs at D = 0.5, at which point the RMS current rating of the capacitors should be greater than half the output current.

Equation 2. GUID-61BCEB66-A882-40B7-9A98-A392683BDB55-low.gif

where

  • D = VOUT / VIN = the module duty cycle

Ideally, the DC and AC components of input current to the buck stage are provided by the input voltage source and the input capacitors, respectively. Neglecting inductor ripple current, the input capacitors source current of amplitude (IOUT – IIN) during the D interval and sink IIN during the 1 – D interval. Thus, the input capacitors conduct a square-wave current of peak-to-peak amplitude equal to the output current. The resultant capacitive component of AC ripple voltage is a triangular waveform. Together with the ESR-related ripple component, Equation 3 gives the peak-to-peak ripple voltage amplitude:

Equation 3. GUID-82082AEC-FC37-4024-BC69-18B9142E1C69-low.gif

Equation 4 gives the input capacitance required for a particular load current:

Equation 4. GUID-DD1C55AB-D737-4756-9A7D-C9FC2F9E8B07-low.gif

where

  • ΔVIN is the input voltage ripple specification.

The TPSM63603 requires a minimum of 2 × 4.7 µF of ceramic type input capacitance. Only use high-quality ceramic type capacitors with sufficient voltage and temperature rating. The ceramic input capacitors provide a low impedance source to the converter in addition to supplying the ripple current and isolating switching noise from other circuits. Additional capacitance can be required for applications with transient load requirements. The voltage rating of input capacitors must be greater than the maximum input voltage. To compensate for the derating of ceramic capacitors, TI recommends a voltage rating of twice the maximum input voltage or placing multiple capacitors in parallel. Table 7-2 includes a preferred list of capacitors by vendor.

Table 7-2 Recommended Input Capacitors
VENDOR(1) DIELECTRIC PART NUMBER CASE SIZE CAPACITOR CHARACTERISTICS
VOLTAGE RATING (V) CAPACITANCE (2)
(µF)
TDK X7R C3216X7R1H475K160AC 1206 50 4.7
Murata X7R GRM31CR71H475KA12L 1206 50 4.7
TDK X7R CGA6P3X7R1H475K250AB 1210 50 4.7
Murata X7S GCM31CC71H475KA03L 1206 50 4.7
(1) Consult capacitor suppliers regarding availability, material composition, RoHS and lead-free status, and manufacturing process requirements for any capacitors identified in this table. See the Third-Party Products Disclaimer.
(2) Nameplate capacitance values (the effective values are lower based on the applied DC voltage and temperature).