ZHCSIB2B December 2017 – October 2019 UCC28064A
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 5 说明 （续）
- 6 Pin Configuration and Functions
- 7 Specifications
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Principles of Operation
- 8.3.2 Natural Interleaving
- 8.3.3 On-Time Control, Maximum Frequency Limiting, Restart Timer and Input Voltage Feed-Forward compensation
- 8.3.4 Distortion Reduction
- 8.3.5 Zero-Current Detection and Valley Switching
- 8.3.6 Phase Management and Light-Load Operation
- 8.3.7 Burst Mode Operation
- 8.3.8 External Disable
- 8.3.9 Improved Error Amplifier
- 8.3.10 Soft Start
- 8.3.11 Brownout Protection
- 8.3.12 Line Dropout Detection
- 8.3.13 VREF
- 8.3.14 VCC
- 8.3.15
System Level Protections
- 8.3.15.1 Failsafe OVP - Output Over-voltage Protection
- 8.3.15.2 Overcurrent Protection
- 8.3.15.3 Open-Loop Protection
- 8.3.15.4 VCC Undervoltage Lock-Out (UVLO) Protection
- 8.3.15.5 Phase-Fail Protection
- 8.3.15.6 CS - Open, TSET - Open and Short Protection
- 8.3.15.7 Thermal Shutdown Protection
- 8.3.15.8 Fault Logic Diagram
- 8.4 Device Functional Modes
-
9 Application and Implementation
- 9.1 Application Information
- 9.2
Typical Application
- 9.2.1 Design Requirements
- 9.2.2
Detailed Design Procedure
- 9.2.2.1 Custom Design With WEBENCH® Tools
- 9.2.2.2 Inductor Selection
- 9.2.2.3 ZCD Resistor Selection RZA, RZB
- 9.2.2.4 HVSEN
- 9.2.2.5 Output Capacitor Selection
- 9.2.2.6 Selecting RS For Peak Current Limiting
- 9.2.2.7 Power Semiconductor Selection (Q1, Q2, D1, D2)
- 9.2.2.8 Brownout Protection
- 9.2.2.9 Converter Timing
- 9.2.2.10 Programming VOUT
- 9.2.2.11 Voltage Loop Compensation
- 9.2.3 Application Curves
- 10Power Supply Recommendations
- 11Layout
- 12Package Option Addendum
- 13器件和文档支持
- 14机械、封装和可订购信息
9.2.2.11 Voltage Loop Compensation
Resistor RZ is sized to attenuate low-frequency ripple to less than 2% of the voltage amplifier output range. This value ensures good power factor and low harmonic distortion on the input current. The voltage on the COMP pin needs to stay above 250 mV to maintain normal operation. If COMP falls below this threshold switching will stop.
The transconductance amplifier small-signal gain is shown in Equation 55:
The voltage-divider feedback gain is shown in Equation 56:
The value of RZ is calculated as shown in Equation 57:
CZ is then set to add 45° phase margin at 1/5th of the line frequency, as shown in Equation 58:
CP is sized to attenuate high-frequency switching noise, as shown in Equation 59:
Standard values should be chosen for RZ, CZ and CP, as shown in Equation 60 to Equation 62.
