Re: DC/DC converter foldback proteccion.

On Thu, 16 Oct 2008 02:05:38 -0700 (PDT), jboix <juan.boix@xxxxxxxxx>
wrote:

On 16 oct, 00:22, John Popelish <jpopel...@xxxxxxxx> wrote:
jboix wrote:
Hello everybody,

   I'm a junior engineer. I need design a 600V DC supply. I have tree
lineal converter of 1000V. And I need protect its because the maximum
current is 1.5mA. I thought protect the power supply with a foldback
circuit but is very difficult for me because I have very high voltage
and very small current.

  Something know what is a possible solution to foldback current? Or
something else?

I have no idea what a "tree lineal converter" is, but I
assume from the title that it is some sort of a DC to DC
converter.  If so, what is the input voltage?  It may be
possible to base the fold back on the input side current,
instead of the output side current.  It won't be as precise,
but may serve.

--
Regards,

John Popelish

Hi,

the lineal converter is a device that connect 12V in the IN pin and
you have 1000V in the OUT pin. This device has a power of 1.5W. I need
3 in paralel because I need 3.5mA. If you had a shortcircuit, it broke
the device. The idea is protect the device with a fooldback circuit. I
know to regulate the device at 600V. The problem is sense 3.5mA at
600V because I don't know any amplifier or device to sense at 600V.


You seem to be inventing words to describe some kind of DC-DC
converter.

In any converter, there is at least one more pin normally, from which
the input and output voltages are measured.

There are two loops; one carrying input current and another carrying
output current. It is possible to measure output current on the output
loop by measuring the current on the lead returning to the
zero-voltage reference. This will not, however, include fault currents
that return to the source by another path.

If the converter has an isolated output, there will be four terminals,
in which case current measured on the output return rail must pass
through the output reference node, regardless of external fault paths.

RL
.

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