ZHCSD93A january 2015 – december 2020 UCC28700-Q1
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 说明
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Detailed Description
-
8 Applications 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 Transformer Parameter Verification
- 8.2.2.2 Output Capacitance
- 8.2.2.3 VDD Capacitance, CDD
- 8.2.2.4 VDD Start-Up Resistance, RSTR
- 8.2.2.5 VS Resistor Divider, Line Compensation, and Cable Compensation
- 8.2.2.6 Input Bulk Capacitance and Minimum Bulk Voltage
- 8.2.2.7 Transformer Turns Ratio, Inductance, Primary-Peak Current
- 8.2.2.8 Standby Power Estimate
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
-
11Device and Documentation Support
- 11.1
Device Support
- 11.1.1
Device Nomenclature
- 11.1.1.1 Capacitance Terms in Farads
- 11.1.1.2 Duty Cycle Terms
- 11.1.1.3 Frequency Terms in Hertz
- 11.1.1.4 Current Terms in Amperes
- 11.1.1.5 Current and Voltage Scaling Terms
- 11.1.1.6 Transformer Terms
- 11.1.1.7 Power Terms in Watts
- 11.1.1.8 Resistance Terms in Ω
- 11.1.1.9 Timing Terms in Seconds
- 11.1.1.10 Voltage Terms in Volts
- 11.1.1.11 AC Voltage Terms in VRMS
- 11.1.1.12 Efficiency Terms
- 11.1.1
Device Nomenclature
- 11.2 Documentation Support
- 11.3 Trademarks
- 11.1
Device Support
- Mechanical, Packaging, and Orderable Information
8.2.2.3 VDD Capacitance, CDD
The capacitance on VDD needs to supply the device operating current until the output of the converter reaches the target minimum operating voltage in constant-current regulation. At this time the auxiliary winding can sustain the voltage to the UCC28700-Q1. The total output current available to the load and to charge the output capacitors is the constant-current regulation target. The equation below assumes the output current of the flyback is available to charge the output capacitance until the minimum output voltage is achieved. There is an estimated 1 mA of gate-drive current in the equation and 1 V of margin added to VDD.
Equation 13. 