ZHCSBB1D July   2013  – March 2018 UCC28740

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      简化应用示意图
      2.      典型伏安图
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Detailed Pin Description
      2. 7.3.2 Valley-Switching and Valley-Skipping
      3. 7.3.3 Startup Operation
      4. 7.3.4 Fault Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Secondary-Side Optically Coupled Constant-Voltage (CV) Regulation
      2. 7.4.2 Primary-Side Constant-Current (CC) Regulation
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Standby Power Estimate and No-Load Switching Frequency
        3. 8.2.2.3 Input Bulk Capacitance and Minimum Bulk Voltage
        4. 8.2.2.4 Transformer Turns-Ratio, Inductance, Primary Peak Current
        5. 8.2.2.5 Transformer Parameter Verification
        6. 8.2.2.6 VS Resistor Divider, Line Compensation
        7. 8.2.2.7 Output Capacitance
        8. 8.2.2.8 VDD Capacitance, CVDD
        9. 8.2.2.9 Feedback Network Biasing
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 VDD Pin
      2. 10.1.2 VS Pin
      3. 10.1.3 FB Pin
      4. 10.1.4 GND Pin
      5. 10.1.5 CS Pin
      6. 10.1.6 DRV Pin
      7. 10.1.7 HV Pin
    2. 10.2 Layout Example
  11. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 开发支持
        1. 11.1.1.1 使用 WEBENCH® 工具定制设计方案
      2. 11.1.2 器件命名规则
        1. 11.1.2.1  电容术语（以法拉为单位）
        2. 11.1.2.2  占空比术语
        3. 11.1.2.3  频率术语（以赫兹为单位）
        4. 11.1.2.4  电流术语（以安培为单位）
        5. 11.1.2.5  电流和电压调节术语
        6. 11.1.2.6  变压器术语
        7. 11.1.2.7  功率术语（以瓦特为单位）
        8. 11.1.2.8  电阻术语（以 Ω 为单位）
        9. 11.1.2.9  时序术语（以秒为单位）
        10. 11.1.2.10 电压术语（以伏特为单位）
        11. 11.1.2.11 交流电压术语（以 VRMS 为单位）
        12. 11.1.2.12 效率术语
    2. 11.2 文档支持
      1. 11.2.1 相关文档
    3. 11.3 接收文档更新通知
    4. 11.4 社区资源
    5. 11.5 商标
    6. 11.6 静电放电警告
    7. 11.7 Glossary
  12. 12机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

8.2.3 Application Curves

The transient response shown in Figure 19 was taken with a 115 VAC, 60 Hz input voltage and a load transition from 0 A to full load. Channel 1 is the load current on a scale of 1 A per division, channel 4 is the otutput voltage on a scale of 1 V per division. The cursor shows the minimum acceptable voltage limit, 4.30 V, under transient conditions. Also note that the output waveform was taken with the probe on TP5 with the ground referenced to TP4 but not using the tip and barrel technique accounting for the high frequency noise seen on the waveform.

The typical switching waveform can be seen in Figure 20. Channel 1 shows the VS pin at 2 V per division and channel 2 shows the MOSFET drain to source voltage at 100 V per division. The scan was taken at 1.8-A load, 115-VAC, 60-Hz input voltage. At this operating point, the switching frequency is dithering between 58.8 kHz and 52.6 kHz due to valley skipping.

The UCC28740 controller employs a unique control mechanism to help with EMI compliance. As shown in Figure 21, the DRV pin, shown as channel 3, drives the gate of the MOSFET with a sequence of pulses in which there will be two longer pulses, two medium pulses, and two shorter pulses at any operating point starting with the amplitude modulation mode. The EMI dithering is not enabled at light load. Figure x shows the result of these varying pulse widths on the CS signal, shown on channel 4. The longer pulses result in a peak current threshold of 808 mV, the medium length pulses are shown measured at 780 mV, and the shorter pulses measure a threshold voltage of 752 mV. This dithering adds to the frequency jitter caused by valley skipping and results in a spread spectrum for better EMI compliance.

UCC28740 appcurve1tr.png
115 VAC, 60 Hz 0 A to 2 A
CH 1 = Load Current, 1 A/DIV
CH 4 = VOUT, cursor shows minimum limit
Figure 19. Transient Response
UCC28740 appcurve1emi.pngFigure 21. EMI Dithering
UCC28740 g2_avgefficiency.gifFigure 23. Average Efficiency
UCC28740 g4_voutiout.gifFigure 25. VOUT vs. IOUT
UCC28740 g6_bodeplot.gif
VIN = 115 VAC IOUT = 2 A
Figure 27. Bode Plot
UCC28740 appcurve1sw.png
CH 1 = VS CH 2 = VDS
IOUT = 1.8 A VIN = 115 VAC, 60 Hz
Figure 20. Switching Waveform
UCC28740 g1_efficiency.gif
Figure 22. Efficiency
UCC28740 g3_noload.gifFigure 24. No Load Power Consumption
UCC28740 g5_controllaw.gifFigure 26. Control Law