Whats a DC-DC convertor?
ManInFl
shifter, or what?
--Byra
Douglas P. McNutt
>What the heck does a DC-DC convertor do? Is it just a regulator/level
>shifter, or what?
It converts one DC voltage to another.
The output may be higher or lower than the input.
The output may or may not be galvanically isolated from the input.
It all depends on what you want and how much you want to pay for it.
-> From the USA. The only socialist country that refuses to admit it. <-
John DeFiore
chop the incoming voltage, an energy storage element (usually an
inductor or flyback transformer) an output filter, and a control loop
to regulate the output voltage. Kind of a DC transformer, because
power out = power in - losses and the voltage and currents change
proportionately. For example you might have 5V in at 5A and 25V out at
8A. With .2A*25V = 5W dissapated in the various elements as heat.
Jurgen van Engelen
|> What the heck does a DC-DC convertor do? Is it just a regulator/level
|> shifter, or what?
|>
How about: it converts a DC voltage to another DC voltage. This can
both be an up- or down conversion and is usually used for power
supply purposes. So it would convert 5V to 12V or v.v. or 24V to
6V dc. Just regard it as a regulator. (Not entirely correct though).
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Thomas D. Kite
> What the heck does a DC-DC convertor do? Is it just a regulator/level
> shifter, or what?
Usually, the term 'DC-DC convertor' refers to a circuit whose DC output,
which is different from the DC input, is derived from some kind of
switching action on the input. That is, it is not a linear regulator, of
the voltage-dropping variety. It has the ability to step up the DC
voltage as well as step it down, which a linear regulator can't do, and
it generally has higher efficiency than the linear regulator, because the
loss in the device is mainly due to the switching action rather than to
ohmic heating.
Potted DC-DC convertors are nice if you want +-12V for an op-amp when you
only have 5V for TTL, for instance.
-Tom
John Nagle
>In <dmcnutt.1...@news-2.csn.net> dmc...@teal.csn.net (Douglas
>P. McNutt) writes:
>>In Article <420egu$a...@newsbf02.news.aol.com>, man...@aol.com
>>>What the heck does a DC-DC convertor do? Is it just a regulator/level
>>>shifter, or what?
>chop the incoming voltage, an energy storage element (usually an
>inductor or flyback transformer) an output filter, and a control loop
>to regulate the output voltage. Kind of a DC transformer, because
>power out = power in - losses and the voltage and currents change
>proportionately. For example you might have 5V in at 5A and 25V out at
>8A. With .2A*25V = 5W dissapated in the various elements as heat.
Most DC-DC converters are basically DC-AC converters driving a
transformer driving an AC-DC converter. There's a control system
in the thing, adjusting the duty cycle of the DC-AC converter to
regulate the output voltage. Switching power supplies and DC-DC
converters are variations on the same theme.
The higher the switching frequency, the smaller the transformer
required. Switching frequencies range from audio frequencies into the
low megahertz. Transformers are typically little things, not big
hunks of metal.
There's another approach to DC-DC conversion, using capacitors and
a "charge pump". These are used when you need very little current,
a few mA or less. Many ICs have charge pumps on-chip, so they can run
off a single supply voltage even though they need several voltages
internally.
John Nagle
Janos Szamosfalvi
: proportionately. For example you might have 5V in at 5A and 25V out at
: 8A. ^^^^^^^^^^^ ^^^^^^^^^^^
^^^
I'd like to have one of these converters.... ;-)
John DeFiore
Sorry- Meant "point" 8 amps. i.e. 800mA.
John DeFiore
Sando) writes:
>
>John DeFiore wrote:
>
>>To elaborate a little, it usually consists of an electronic switch to
>>chop the incoming voltage, an energy storage element (usually an
>>inductor or flyback transformer) an output filter, and a control loop
>>to regulate the output voltage. Kind of a DC transformer, because
>>power out = power in - losses and the voltage and currents change
at
>
>
>25W in with 200W out - that ought to really change electric vehicle
>technology!! I can hear the oil companies scrambling already :-)
>
>Cheers,
>
>Scott
>
>O
OK, I'm taking a lot of heat for this typo... :) It was "Point eight
amps" or 800mA that I intended for the output current which would give
20W out with 5W losses or an efficiency of 80%, which is more or less
typical. (Yes, you can do better- even up to 96% if you try hard and
don't mind spending some extra money.)
Sorry for the goof,
John