SDAA026 June   2025 TPSI3052

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Using a Solid-State Relay as an Isolated 15V Supply
  6. 3Topology of Totem Pole PFC for Applying Turn On Switch
  7. 4Original Implementation for Driving PFC Slow Switch at High-side and Low-side
  8. 5Achieving Performance for Driving PFC Slow Switch at High-side and Low-side
  9. 6Test Results Comparing Before and After for High-side Implementation
  10. 7Summary
  11. 8References

4 Original Implementation for Driving PFC Slow Switch at High-side and Low-side

When the DC input voltage is applied and the polarity is reversed (live terminal (-) voltage, neutral terminal (+) voltage), the slow switch high side FET turned on, but the existing charge pump circuit cannot generate VDD voltage. Since this is a DC input, this does not switch, so the high-side FET cannot be turned on, and current flows to the parasitic diode, causing heat generation and reduced efficiency.

Conventional Circuit for Operating PFC Slow Switch at High-side (Q1) Figure 4-1 Conventional Circuit for Operating PFC Slow Switch at High-side (Q1)