seeking advice on SMPS on a chip solution

Samudra Haque samudra.haque at
Wed Jul 6 13:14:38 CDT 2005

Hello, This is my first post on Tacos mailing list, so let me
introduce myself, I am N3RDX and S21X, and have been tinkering with
radios (HF, VHF, Satellite, Microwave) in Bangladesh until recently.
My current interest is "broadband multi-service long range hybrid
communication" devices. My commercial experience is IT, Internet and
Satellite industry.

I have an issue where I would like the advice of experienced engineers 
I have been studying the feasibility of designing a SMPS power supply
to replace a linear transformer, unregulated DC power supply with the
following characteristics:

I/P 220VAC
Transformer: Iron Core
O/P variable unregulated DC 24-60VDC tapped. 3.75 Amps maximum. O/P is
selected to accomodate the length of the umbilical cable from indoor
to outdoors, and the resultant loss of voltage: the device in use
requires 24 Volts 3.75 Amps max, so the output is adjusted to
accomodate 24/33/42/50/59 VDC to allow for the voltage drop to 24 VDC
at the destination.

I want to modernise this power supply with a SMPS and get rid of the
v-e-r-y heavy transformer. I was toying with using MAXIM or National
Semiconductor PWM chips, but then found and
their TOPSSwitch-GX family of SMPS on a chip products. Please see, of particular note is
that that same chip family can be used to supply low power to high
power (250W @250-380VDC) so perhaps it could be a useful project to
build as a basis for a modern universal power supply for hams. The
chip seems to be complete and upto 34W can be used without heatsinks.

Does anyone have any experience with this product please ?
Thank you.


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