Post by thread:[EE]How do you use an EL LCD with only 5V regulate

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_OUTyangres2002TakeThisOuTrogers.com new grad, U of T electrical engineering

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 >.....yangres2002KILLspam@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" speffKILLspaminterlog.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

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

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 <.....speffKILLspam.....interlog.com> wrote: {Quote hidden}> > 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 > >EraseMEyangres2002spam_OUTTakeThisOuTrogers.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" > speffspam_OUTinterlog.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 > > >

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_piclistKILLspamembedinc.com> wrote: {Quote hidden}> > 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 >

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" KILLspamspeffKILLspaminterlog.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

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

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 RemoveMEyangres2002TakeThisOuTrogers.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 spamBeGoneyangres2002spamBeGonerogers.com new grad, U of T electrical engineering

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