ZHCSBB1D July 2013 – March 2018 UCC28740
PRODUCTION DATA.
- 1 特性
- 2 應用
- 3 說明
- 4 修訂歷史記錄
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Detailed Description
-
8 Application and Implementation
- 8.1 Application Information
- 8.2
Typical Application
- 8.2.1 Design Requirements
- 8.2.2
Detailed Design Procedure
- 8.2.2.1 Custom Design With WEBENCH® Tools
- 8.2.2.2 Standby Power Estimate and No-Load Switching Frequency
- 8.2.2.3 Input Bulk Capacitance and Minimum Bulk Voltage
- 8.2.2.4 Transformer Turns-Ratio, Inductance, Primary Peak Current
- 8.2.2.5 Transformer Parameter Verification
- 8.2.2.6 VS Resistor Divider, Line Compensation
- 8.2.2.7 Output Capacitance
- 8.2.2.8 VDD Capacitance, CVDD
- 8.2.2.9 Feedback Network Biasing
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機械、封裝和可訂購信息
8.2.2.7 Output Capacitance
The output capacitance value is often determined by the transient-response requirement from the no-load condition. For example, in typical low-power USB-charger applications, there is a requirement to maintain a minimum transient VO of 4.1 V with a load-step ITRAN from 0 mA to 500 mA. Yet new higher-performance applications require smaller transient voltage droop VOΔ with ITRAN of much greater amplitude (such as from no-load to full-load), which drives the need for high-speed opto-coupled voltage feedback.
where
- tRESP is the time delay from the moment ITRAN is applied to the moment when IFB falls below 1 µA
Additional considerations for the selection of appropriate output capacitors include ripple-current, ESR, and ESL ratings necessary to meet reliability and ripple-voltage requirements. Detailed design criteria for these considerations are beyond the scope of this datasheet.