ZHCSSS8 august 2023 TPS552872
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 描述
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 VCC Power Supply
- 7.3.2 EXTVCC Power Supply
- 7.3.3 Input Undervoltage Lockout
- 7.3.4 Enable and Programmable UVLO
- 7.3.5 Soft Start
- 7.3.6 Shutdown
- 7.3.7 Switching Frequency
- 7.3.8 Switching Frequency Dithering
- 7.3.9 Inductor Current Limit
- 7.3.10 Internal Charge Path
- 7.3.11 Output Voltage Setting
- 7.3.12 Output Current Monitoring and Cable Voltage Droop Compensation
- 7.3.13 Output Current Limit
- 7.3.14 Overvoltage Protection
- 7.3.15 Output Short Circuit Protection
- 7.3.16 Power Good
- 7.3.17 Constant Current Output Indication
- 7.3.18 Thermal Shutdown
- 7.4 Device Functional Modes
- 8 Application and Implementation
- 9 Device and Documentation Support
- 10Mechanical, Packaging, and Orderable Information
8.2.2.4 Input Capacitor
In buck mode, the input capacitor supplies high ripple current. The RMS current in the input capacitors is given by Equation 14.
Equation 14. 
where
- ICIN(RMS) is the RMS current through the input capacitor
- IOUT is the output current
The maximum RMS current occurs at the output voltage is half of the input voltage, which gives ICIN(RMS) = IOUT / 2. Ceramic capacitors are recommended for their low ESR and high ripple current capability. A total of 20 µF effective capacitance is a good starting point for this application. Add a 0.1-μF/0402 package ceramic capacitor and place it close to VIN pin and GND pin to suppress high frequency noise.