ZHCSQ73 april 2023 TPS552892-Q1
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 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
8.2.2.5 Output Capacitor
In boost mode, the output capacitor conducts high ripple current. The output capacitor RMS ripple current is given by Equation 15, where the minimum input voltage and the maximum output voltage correspond to the maximum capacitor current.
where
- ICOUT(RMS) is the RMS current through the output capacitor
- IOUT is the output current
In this example, the maximum output ripple RMS current is 1.7 A.
The ESR of the output capacitor causes an output voltage ripple given by Equation 16 in boost mode.
where
- RCOUT is the ESR of the output capacitance
The capacitance also causes a capacitive output voltage ripple given by Equation 17 in boost mode. When input voltage reaches the minimum value and the output voltage reaches the maximum value, there is the largest output voltage ripple caused by the capacitance.
Typically, a combination of ceramic capacitors and bulk electrolytic capacitors is needed to provide low ESR, high ripple current, and small output voltage ripple. From the required output voltage ripple, use Equation 16 and Equation 17 to calculate the minimum required effective capacitance of the COUT.
Add a 0.1-μF/0402 package ceramic capacitor and place it close to VOUT pin and GND pin to suppress high frequency noise.