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When reverse engineering the electronics of a Wattmeter from AliExpress, I came across a remarkable Chinese switching DC-DC converter chip that I had never seen before: the FT8430. I want to bring this to your attention here.

  • Only 3 pins
  • Maximum input voltage 300V
  • Switching frequency 50kHz

The manufacturer is Fremont Micro Devices (FMD). Apparently they don't need the west because their website is only in Chinese. 

FT8430 high input voltage buck switching DC-DC converter in SOT23-3
FT8430 high input voltage buck switching DC-DC converter in SOT23-3

FT8430 High input voltage buck converter in SOT23-3 footprint
FT8430 High input voltage buck converter in SOT23-3 footprint

The maximum input voltage is with 300V much higher than comparable chips from the west, so you can supply directly a from the rectified mains voltage:

Single chip 230VAC to 5V smps buck converter
Single chip 230VAC to 5V smps buck converter

No electrical connection to the GND

This design is remarkably clever because the IC can only indirectly measure the output voltage.

How does this work?

This shows that the days of the Chinese copying everything are over.

The FT8430 is not for sale in the west

Why isn’t the FT8430 for sale at Mouser or Digikey?

Do you have any comments about the website? Please let me know.