TIDT369A November   2023  – April 2024

 

  1.   1
  2.   Description
  3.   Features
  4. 1Applications
  5.   Resources
  6. 2System Description
    1. 2.1 System Block Diagram
    2. 2.2 Key System Specification
    3. 2.3 Design Consideration
      1. 2.3.1 Boost Inductor Design
      2. 2.3.2 High Frequency Power Switch Selection
      3. 2.3.3 Input AC Voltage Sensing
      4. 2.3.4 Bulk Voltage Sensing
      5. 2.3.5 Input Current Sensing
      6. 2.3.6 Baby Boost Design
      7. 2.3.7 Relay
      8. 2.3.8 Protection
        1. 2.3.8.1 Over Voltage Protection
        2. 2.3.8.2 Over Current Protection
  7. 3Power Up
    1. 3.1 Required Equipment
    2. 3.2 Considerations
    3. 3.3 Start-Up Sequence
  8. 4Testing Results
    1. 4.1 Start-Up Waveform
    2. 4.2 THD Performance
    3. 4.3 Power Factor
    4. 4.4 Efficiency
      1. 4.4.1 Efficiency Graph
      2. 4.4.2 Efficiency Data
    5. 4.5 E-meter Performance
      1. 4.5.1 E-meter Graphs
      2. 4.5.2 E-meter Data
    6. 4.6 Load Transients
    7. 4.7 Input Current Waveforms
    8. 4.8 AC Drop Test
    9. 4.9 Thermal Images
  9. 5External Reference

2.3.6 Baby Boost Design

To maintain holdup time and reduce bulk capacitance, a baby boost converter is added between the PFC and DC/DC as shown in the Figure 2-1. The baby boost converter is a compact boost converter that only operates during AC dropout events. During normal operation, the baby boost converter is off and bypassed by a MOSFET. When AC line dropout occurs, the Bypass FET turns off, baby boost converter turns on to ensure VBB maintains above the UVLO level for the isolated DC/DC converter. In order to minimize the magnetic dimension, the switching frequency of baby boost is set at 500KHz.