SLVSGJ5 April   2022 TPSM63604

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  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 System Characteristics
    7. 7.7 Typical Characteristics
    8. 7.8 Typical Characteristics (VIN = 12 V)
    9. 7.9 Typical Characteristics (VIN = 24 V)
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Input Voltage Range (VIN1, VIN2)
      2. 8.3.2  Adjustable Output Voltage (FB)
      3. 8.3.3  Input Capacitors
      4. 8.3.4  Output Capacitors
      5. 8.3.5  Switching Frequency (RT)
      6. 8.3.6  Precision Enable and Input Voltage UVLO (EN/SYNC)
      7. 8.3.7  Frequency Synchronization (EN/SYNC)
      8. 8.3.8  Power Good Monitor (PG)
      9. 8.3.9  Adjustable Switch-Node Slew Rate (RBOOT, CBOOT)
      10. 8.3.10 Bias Supply Regulator (VCC, VLDOIN)
      11. 8.3.11 Overcurrent Protection (OCP)
      12. 8.3.12 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1 – High-Efficiency 4-A Synchronous Buck Regulator for Industrial Applications
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2 Output Voltage Setpoint
          3. 9.2.1.2.3 Switching Frequency Selection
          4. 9.2.1.2.4 Input Capacitor Selection
          5. 9.2.1.2.5 Output Capacitor Selection
          6. 9.2.1.2.6 Other Connections
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2 – Inverting Buck-Boost Regulator with Negative Output Voltage
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Output Voltage Setpoint
          2. 9.2.2.2.2 IBB Maximum Output Current
          3. 9.2.2.2.3 Switching Frequency Selection
          4. 9.2.2.2.4 Input Capacitor Selection
          5. 9.2.2.2.5 Output Capacitor Selection
          6. 9.2.2.2.6 Other Considerations
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Thermal Design and Layout
    2. 11.2 Layout Example
      1. 11.2.1 Package Specifications
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Development Support
        1. 12.1.2.1 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.3 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 is 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 TPSM63604 requires a minimum of two 10-µF ceramic input capacitors, preferably with X7R or X7S dielectric and in 1206 or 1210 footprint. Additional capacitance can be required for applications to meet conducted EMI specifications, such as CISPR 11 or CISPR 32.

Table 8-2 includes a preferred list of capacitors by vendor. To minimize the parasitic inductance in the switching loops, position the ceramic input capacitors in a symmetrical layout close to the VIN1 and VIN2 pins and connect the capacitor return terminals to the PGND pins using a copper ground plane under the module.

Table 8-2 Recommended Ceramic Input Capacitors
Vendor(1) Dielectric Part Number Case Size Capacitance (µF)(2) Rated Voltage (V)
TDK X7R C3216X7R1H106K160AC 1206 10 50
Murata X7S GCM32EC71H106KA03K 1210 10 50
AVX X7R 12105C106MAT2A 1210 10 50
Murata X7R GRM32ER71H106KA12L 1210 10 50
(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).

As discussed in Section 10, an electrolytic bulk capacitance (68 µF to 100 µF) provides low-frequency filtering and parallel damping to mitigate the effects of input parasitic inductance resonating with the low-ESR, high-Q ceramic input capacitors.