SLLA646 August   2024 ISO6520 , ISO6521

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Where are Digital Isolators Commonly Used?
    2. 1.2 What is Functional Isolation?
    3. 1.3 Key Benefits of Functional Isolation
  5. 2Application Use Cases
    1. 2.1 Telecom Power Supplies
      1. 2.1.1 48V Isolated DC-DC
      2. 2.1.2 48V Non-Isolated DC-DC
    2. 2.2 Server Power Supply
      1. 2.2.1 Totem-Pole Power Factor Correction Stage
      2. 2.2.2 Half-Bridge LLC Stage
    3. 2.3 AC - DC Power Supply in Pluggable Wall-Chargers
      1. 2.3.1 Introduction
      2. 2.3.2 Topology Details
      3. 2.3.3 Using ISO65xx for Reliable PWM Signaling
    4. 2.4 Semiconductor Test and Measurement
  6. 3Conclusion
  7. 4References

2.1.2 48V Non-Isolated DC-DC

Non-isolated Inverted Buck-Boost (IBB) topologies are ideal for Power amplifier applications where Power Supply Unit (PSU) output voltage needs to be changed based on the demand, derived from the -48V input.

A digital controller referenced to system ground is powered up using auxiliary power sources. This controller provides PWM signal as per the required output voltage level. A typical IBB implementation is as shown in Figure 2-2. Note that the switching power FETs (Q1 and Q2) are not referenced to the same reference node as the controller IC.

Typical Inverted Buck-Boost implementation With ISO65xxFigure 2-2 Typical Inverted Buck-Boost implementation With ISO65xx

ISO65xx family of functional isolators can be used to faithfully block the switching noise across the isolation barrier and level shift the PWM signal from the controller to the power FET. High immunity to common mode noise (100kV/us) is essential to ensure reliable system performance over device lifetime.

Functional Isolation working voltage (VIOWM) needed between the controller and the FETs can be as high as 100V. ISO65xx blocks the common mode voltage for reliable FET operation.