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'[EE]How do you use an EL LCD with only 5V regulate'
2005\05\18@133353 by Wallace Yang

picon face
Dear all:

I would like to use an electroluminescent (EL) LCD
because it boasts a very low current consumption (~2mA
I'm not sure if this is AC).  However, its lighting
power source requires AC100Vrms, 400Hz.  The
application that I'm working on can only use a 9V
battery and a 5V regulator.  

1) Is there some IC that can convert DC5V into
AC100Vrms, 400Hz?

2) The current probably will not be DC2mA will it?  If
not, what might it be?

Thanks in advance.

Wallace Yang
spam_OUTyangres2002TakeThisOuTspamrogers.com
new grad, U of T electrical engineering

2005\05\18@140121 by Spehro Pefhany

picon face
At 01:33 PM 5/18/2005 -0400, you wrote:
>Dear all:
>
>I would like to use an electroluminescent (EL) LCD
>because it boasts a very low current consumption (~2mA
>I'm not sure if this is AC).  However, its lighting
>power source requires AC100Vrms, 400Hz.  The
>application that I'm working on can only use a 9V
>battery and a 5V regulator.
>
>1) Is there some IC that can convert DC5V into
>AC100Vrms, 400Hz?

For a one-off you should probably just buy a compatible inverter
module unless you're planning a diversion into SMPS design.
Or use one with an LED backlight.

>2) The current probably will not be DC2mA will it?  If
>not, what might it be?

Probably similar order of magnitude to an LED backlight
these days, for similar brightness. It will be highly dependent
on the area of the LCD. Tens or scores of mA at 5V, I'd guess.

>Thanks in advance.
>
>Wallace Yang
>.....yangres2002KILLspamspam@spam@rogers.com
>new grad, U of T electrical engineering

Who was your thesis advisor?

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speffspamKILLspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
>>>Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


2005\05\18@140444 by olin_piclist

face picon face
Wallace Yang wrote:
> I would like to use an electroluminescent (EL) LCD
> because it boasts a very low current consumption (~2mA
> I'm not sure if this is AC).  However, its lighting
> power source requires AC100Vrms, 400Hz.  The
> application that I'm working on can only use a 9V
> battery and a 5V regulator.
>
> 2) The current probably will not be DC2mA will it?

Not unless you have found a way to redifine the laws of physics.

> not, what might it be?

You can work this out yourself.  Figure the power going into the EL
backlight.  Now figure current that must be drawn from 5V to get that power.
That's the theoretical minimum current it will take.  In practise the
conversion from 5V to 100VAC won't be 100% efficient, so more power will
need to be drawn from the 5V.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\05\18@140834 by Tarun Grover

picon face
This place sells EL Inverter modules - although I'm not sure this is what you're looking for, but it's worth a look anyways.

http://www.globalsources.com/manufacturers/EL-Inverter.html

On 5/18/05, Spehro Pefhany <.....speffKILLspamspam.....interlog.com> wrote:
{Quote hidden}

>

2005\05\18@143545 by Tarun Grover

picon face
Sorry, forgot to mention earlier, but there is a line of IC's from Supertex that do just what you want. They are available at mouser and I am linking to one of them.

http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=401660&e_categoryid=266&e_pcodeid=68904

Hope that helps.

-Tarun.

On 5/18/05, Olin Lathrop <@spam@olin_piclistKILLspamspamembedinc.com> wrote:
{Quote hidden}

>

2005\05\18@161906 by Spehro Pefhany

picon face
At 02:35 PM 5/18/2005 -0400, you wrote:
>Sorry, forgot to mention earlier, but there is a line of IC's from Supertex
>that do just what you want. They are available at mouser and I am linking to
>one of them.
>
>http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=401660&e_categoryid=266&e_pcodeid=68904
>
>Hope that helps.

Good call, Tarun. Very importantly, the proper inductor is also available
from the same source, and at a very reasonable price.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
KILLspamspeffKILLspamspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
>>>Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff



2005\05\18@190849 by William Chops Westfield

face picon face

On May 18, 2005, at 10:33 AM, Wallace Yang wrote:

> I would like to use an electroluminescent (EL) LCD
> because it boasts a very low current consumption (~2mA
> I'm not sure if this is AC).  However, its lighting
> power source requires AC100Vrms, 400Hz.

Hmm.  About 200mW, then.  That's not particularly low
POWER consumption

> 1) Is there some IC that can convert DC5V into
> AC100Vrms, 400Hz?

Maybe.  Several have been suggested (supertex, micrel, durel),
but they tend to produce somewhat lower voltages; usually expressed
as Vp-p (peak-to-peak); you may recall an earlier discussion about
how 100V rms turns out to be something like 280Vp-p; most of the single
chip El drivers put out less than 160Vp-p, and seem to be aimed at EL
panels ranging from watch-sized to cellphone size.
You might be able to use one of the relatively cheap inverters aimed at
computer "case mods" and/or EL "wire", such as:
http://shopping.netledger.com/s.nl/c.ACCT76399/sc.2/category.11/it.A/
id.807/.f
>
> 2) The current probably will not be DC2mA will it?  If
> not, what might it be?
>
Power is constant, so you're looking at 200mW plus conversion losses;  
30mA or
so, probably (from 9V.  about 50mA from 5V)  You'll note that 30mA at  
9V will
drive quite a lot of conventional LEDs...

BillW

2005\05\19@221232 by Wallace Yang

picon face
Thanks to all who replied.  

In my application, I would like to use a 4x20char LCD
with backlight.  Low power consumption is of primary
importance.  As I understand, LED backlit LCDs draw on
the order of 100mA at 5V.  My current plan is to use
EL backlighting, which might be slightly better
(although more complicated to implement).  Does anyone
have a better alternative?

Wallace Yang
RemoveMEyangres2002TakeThisOuTspamrogers.com
new grad, U of T electrical engineering

=====================================================
Original message:
-----------------------------------------------------
Dear all:

I would like to use an electroluminescent (EL) LCD
because it boasts a very low current consumption (~2mA
I'm not sure if this is AC).  However, its lighting
power source requires AC100Vrms, 400Hz.  The
application that I'm working on can only use a 9V
battery and a 5V regulator.  

1) Is there some IC that can convert DC5V into
AC100Vrms, 400Hz?

2) The current probably will not be DC2mA will it?  If
not, what might it be?

Thanks in advance.

Wallace Yang
spamBeGoneyangres2002spamBeGonespamrogers.com
new grad, U of T electrical engineering

2005\05\20@020710 by William Chops Westfield

face picon face
On May 19, 2005, at 7:12 PM, Wallace Yang wrote:

> application, I would like to use a 4x20char LCD
> with backlight.  Low power consumption is of primary
> importance.  As I understand, LED backlit LCDs draw on
> the order of 100mA at 5V.

I don't see why that should need to be true with modern LEDs; it sounds
like a spec from the "dark ages" of 20mCd yellow-green LED panels with
20+ LEDs for 'even illumination.'  Between modern ultrabright LEDs and
better understanding of light distribution, you ought to be able to do
much better.  See for instance:

www.goldmine-elec-products.com/prodinfo.asp?number=G14922
http://home.clear.net.nz/pages/joecolquitt/led+lcd.html

BillW

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