I have a special power supply requirement for Agro Based Applications..

After stepping down conventional primary 230VAC, 50Hz Single phase single line supply to secondary 80VAC (4Amps to 6Amps), I need to convert the secondary voltage to dual DC supplies of 5VDC (3Amps) and 15VDC (500mAmps).

The 5VDC is to power my own sensor board designs and the 15VDC is to trigger a relay in it for only special cases.

However, since I have a limitation which compels me to connect N number of boards to the DC power converted from the same single phase AC supply, I estimate a voltage drop to even as low as 15VAC at secondary once Nth board is connected.

There are very few reference designs for power supply categories below 80VAC and I am at a loss here. Can anyone suggest a suitable cost effective method to achieve this low AC to Dual DC conversion?


  • 1
    \$\begingroup\$ Start with a 120 V AC design and tweak the details for 80 V AC. For example, you might use different transformer radios. \$\endgroup\$ – Brian Carlton May 25 '17 at 3:57
  • \$\begingroup\$ I would start with a transformer that steps down to about 15 V AC. A transformer should be (approximately) a constant voltage supply - adding more loads while keeping within the rating of the transformer will not reduce the voltage significantly. \$\endgroup\$ – Peter Bennett May 25 '17 at 4:09
  • \$\begingroup\$ So you need a PSU with input in the range of 15-80VAC, right? \$\endgroup\$ – Todor Simeonov May 25 '17 at 9:11

Search for "high voltage buck converter IC" and you will find many chips from which to select. Analog Devices makes wide input range chips. Take a look at the LTC3895 and LTC7801 as examples. 4-140 volt input range.


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