Boost Converter

[New User ^_^]

Hi All,

First of all, I'd like to thank to those who answered my question
before regarding boost converter IC. Actually, I'm not sure the
difference between boost converter and boost switching regulator.

For example, I want to boost the input voltage by 10V, i.e. Vout = Vin
+ 10V. Shall I use boost converter or boost switching regulator??

What does it mean by the following terms?
Fixed 3.3-V High-Efficiency Boost Converter
Adjustable 3.3-V High-Efficiency Boost Converter
Fixed output voltage?? Adjustable output voltage??

For my case, shall I use UC2577-ADJ or LM3478 if I just want to boost
Vin by 10V for 3V<=Vin<=10 ??

Thanks for your help in advance.

Regards,
Will

 

[Anders F]

"New User ^_^" <chickenwing2010@yahoo.com.hk> wrote in message
news:ee4f941.0411190700.275fe69a@posting.google.com...

Hi All,

First of all, I'd like to thank to those who answered my question
before regarding boost converter IC. Actually, I'm not sure the
difference between boost converter and boost switching regulator.

Same! The first is just short for the latter...

What does it mean by the following terms?
Fixed 3.3-V High-Efficiency Boost Converter
Adjustable 3.3-V High-Efficiency Boost Converter
Fixed output voltage??

Set by the device (controller)

Adjustable output voltage??

Set by you (usually by a resistor divider)

For my case, shall I use UC2577-ADJ or LM3478 if I just want to boost
Vin by 10V for 3V<=Vin<=10 ??

Most designs boost to a stable voltage. You might do some design to add the
input voltage to the feedback. Bust most probably you will be satisfied with
ie. 20V out from 3-10V input?

/A

Thanks for your help in advance.

Regards,
Will

 

[kell]

I am wondering about your post. I can't think why you would
want your otuput voltage to wander up and down.
Because your input voltage will probably vary with load.
Do you really want a converter with an output that is not regulated?

If the answer to that one is yes, one way is to use a
converter with an isolated output, like
a push-pull converter. That way you can just take the output
and stack it on top of your input power source.

Push-pull converters differ from the boost
converter topology in that they use a transformer instead
of a single inductor. Push-pulls will put out more power.

What is the application?

 

[Fred Bartoli]

"Fred Bloggs" <nospam@nospam.com> a écrit dans le message de
news:41A0C673.7070804@nospam.com...

... and good enough for high side MOSFET(s) gate drive bias.

Ah, I missed that. Yes indeed.

--
Thanks,
Fred.

 

[Ken Smith]

In article <41a0c104$0$31624$626a14ce@news.free.fr>,
Fred Bartoli <fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:
[...]

Or if the OP doesn't mind a -2mV/K temperature dependency, here's the
simpler :

[.. diagram snipped ...]


Linear makes an "isolated flyback" converter that contains much the same
function as the PNP transistor. If the OP can stand the inaccuracy it
has, it would be worthwhile looking at it.


Unfortunately the Linear web site is still all screwed up so I can't find
it and post the number. Its something like LT1723 or there abouts.

--
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kensmith@rahul.net forging knowledge

 

[Fred Bloggs]

New User ^_^ wrote:

For my case, shall I use UC2577-ADJ or LM3478 if I just want to boost
Vin by 10V for 3V<=Vin<=10 ??

In order to obtain Vout= Vin + 10V which is equivaleNt to
(Vout-Vin)=10V=~8*Vref of the UC2577, you will have to do something like
this:

View in a fixed-width font such as Courier.


..
..
..
.. L1
.. Vin >---+---UUUUU-----+
.. | ===== |
.. | |
.. +------------+ |
.. | Vin | | D1
.. | sw +----+-----|>|--+---+---------+------> Vin + 10
.. | | | | |
.. | | === | /
.. | | | | 20K OA=LT1013
.. | UC2577 | GND | /
.. | | | \ or other
.. | | OA |/| |
.. | | 6.0K /+|-------+ single-
.. | (2)+----+---/\/\--+---< | |
.. | FB | | | \-|--+ / supply
.. | | / | |\| | 10K
.. | | 2,0K | | | / 1MHz GBW
.. | | / | gnd | \
.. | | \ | | |
.. | GND | | | | gnd
.. +-----+------+ gnd | 10K |
.. | +---/\/\--+
.. +-----gnd |
.. | 20K |
.. | Vin >---/\/\--+
.. |
.. -------+--------------------------------------------> GND
..
..

 

[Mac]

On Fri, 19 Nov 2004 07:00:06 -0800, New User ^_^ wrote:

Hi All,

First of all, I'd like to thank to those who answered my question
before regarding boost converter IC. Actually, I'm not sure the
difference between boost converter and boost switching regulator.

For example, I want to boost the input voltage by 10V, i.e. Vout = Vin
+ 10V. Shall I use boost converter or boost switching regulator??

It is VERY unclear what you are trying to do.

I'm going to ask some questions, and I suggest you take the time to answer
them. If you don't know the answers to some of them, then you can just
say that you don't know. If you don't know the answers to ANY of them,
then you are not ready to select an IC.

1) What range might Vin be?

2) How much current do you need to supply from Vout?

3) How does Vin vary with time? Is it a non-rechargeable battery which
drains slowly over time? Is it a rechargeable battery which slowly
drains but might experience a rapid rise when the charger comes on-line?
Is it a music signal? Voice? What?

4) What if, instead of producing Vout = Vin + 10, we could just produce
some nice fixed voltage such as 20 volts or 48 volts or something? Would
that meet your needs? It might be easier to do this than to create Vin +
10 volts.

5) What, if any stable voltage supplies do you have available to you?

It is important that you answer these questions, because a variety of
people are probably going to give up trying to help you if you don't start
telling us a little bit more about your application.

[snip]

Thanks for your help in advance.

You can best show your appreciation by supplying answers to the questions
that I and others have asked you. ;-)

Regards,
Will

--Mac

 

[Ken Smith]

In article <41a0c104$0$31624$626a14ce@news.free.fr>,
Fred Bartoli <fred._canxxxel_this_bartoli@RemoveThatAlso_free.fr_AndThisToo> wrote:
[...]

Or if the OP doesn't mind a -2mV/K temperature dependency, here's the
simpler :
You can compensate for the -2mV/K like this:

Editted diagram:

.------------------------------.
| |
. | L1 |
. Vin >---o---UUUUU-----+ |
. | ===== | |
. | | |
. +------------+ | |
. | Vin | | D1 |
. | sw +----+-----|>|--+-----)-------+------> Vin + 10
. | | | | |
. | | === +---. |
. | | | | | .-.
. | UC2577 | GND | | | |20K
. | | | V | |
. | | | - '-'
. | | --- | |
. | (2)+-----------+---+----/ ^--+---'
. | FB | | !
. | | .-. ! Small sig PNP
. | | | | /
. | | R1 | | \ R2
. | | '-' /
. | GND | | !
. +-----+------+ | V
. | === ---
. +-----gnd GND !
. | GND
. |
. |
. -------+--------------------------------------------> GND
(created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)

R1
-------- = Vfb/10V (about)
R1 + R2

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kensmith@rahul.net forging knowledge