Re: [uCsimm] where can I get a CCFT inverter for the LM32019T ?

From: Tom Walsh (tom@cyberiansoftware.com)
Date: Wed Feb 28 2001 - 00:49:06 EST


byonic@gmx.net wrote:
>
> Hello ucsimm@uClinux.com,
>
> I need a CCFT inverter for the SHARP LM32019T .
> Is there any store that would ship the inverter to Europe and which
> inverter could I use for the LCD ?
> (Any inverter <1500Vrms, is that right ?)
>

I got my inverters from 'http://www.flat-panel.com', you have to contact
them direct, they don't list them on thier website, but they have the
inverters + pig-tail leads for the power (remember to TELL them that you
want the power leads also).

With the inverters, you have to observe: power output, frequency, and
voltage. If the voltage / current output of the inverter is too high it
will destroy the CCFT... So Think of the CCFT as if it was a
dead-short that glows very brightly (like neon).

Here is some data that I got from an LCD engineer regarding a question
that I had on inverters, hope this sheds some "light" (pun intended):

---------------------------- begin
---------------------------------------------

> Dallas
>
> Selection of Inverters for CCFT Backlit Displays
> Leon Drucker, Sr. Field Technical Manager
>
> INTRODUCTION
> There are several factors to consider when selecting an inverter for
> use with "Cold Cathode Fluorescent Tube" Backlit Displays. Aside from being
> able to meet the lamp specifications of power requirements it is also
> important to be aware of physical constraints such as size and connection
> method.
>
> FACTORS
> Number of Tubes
> Multiple inverters, all running asynchronous of each other can cause some
> severe visual interference problems with the scanning rates. It is best to
> have one controllable inverter supplying tube current for all of the CCFT's.
> Kick Off or Start Voltage
> If a voltage less than the minimum starting voltage is applied to the tube
> it will not light. The starting voltage of most CCFT is both time and
> temperature dependent. The older and colder the tube, the higher the
> starting voltage. The output voltage of the inverter, measured at the CCFT,
> must be equal to or greater than the minimum starting or discharge voltage
> specified at cold temperature and maximum life of the tube
> Lamp Current
> The brightness of any CCFT is directly proportional to the RMS tube current.
> Exceeding the recommended tube current can produce excess heating, which
> could cause discoloration of the display around the location of the tube. If
> the tube current is increased above nominal then the tube's useful life is
> decreased.
> Operating Voltage and Frequency
> The voltage across the tube after it has been lit may decrease slightly as
> the current through the tube is increased. The operating frequency of the
> inverter should be chosen to be completely compatible with the LCD module.
> Higher frequencies can put restrictions on the packaging and the
> interconnecting lead capacitance between the inverter and the CCFT.
> Dimming
> In many applications it is desirable to change the brightness of the
> backlight. In analog dimming the amplitude of the current is changed. Analog
> dimming is considered to be more "noise-free" technique which loans itself
> nicely to low power single tube applications. In PWM dimming the output
> current is switched on and off. This technique offers high system
> efficiencies and brightness tracking. Multiple tube higher power
> applications are more easily and reliably handled by PWM.
> Packaging
> Connectors on inverter must match those on the tube. Cable length must be
> long enough to meet packaging constraints. Size, cost and efficiency should
> be considered.
>
>
> MAJOR CCFT INVERTER SUPPLIERS
> Xentek
> 1770 La Costa Meadows Drive, San Marcos, CA 92069
> Tel. (760)471-4001 Fax. (760)471-4021
>
> Endicott Research Group
> 2601 Wayne Street, PO Box 269, Endicott, NY 13760
> Tel. (800)215-5866 Fax. (607)754-9255
>
> Linfinity
> 11861 Western Avenue, Garden Grove, CA 92841
> Tel. (714)898-8121
>
> TDK
> San Francisco Regional
> 2055 Gateway Place Suite 200 San Jose, CA 95110
> Tel. (408)437-9585 Fax. (408)437-9591
>
> Major Connector Supplier for CCFT
>
> JST Corporation
> 1967 South Lakeside Drive
> Waukegan, IL 60085
> Tel. (800) 947-1110 Fax. (847) 473-1044
>
> Disclaimer/Notes
>
> Inverters are 5Volt input with matching connectors to panels
> For 12Volt input or PC mount please refer to individual Mfg. guides
> For special dimming requirements please refer to Mfg. Specs.
> Displays are taken from latest Sharp Display Product Update Sheets dated
> 8/24/98
> For displays not listed or without inverter selected please refer to
> suggested manufactures
> For connector information please see display specifications
> Please visit our web site at www.sharpsma.com for data sheets and
> application notes
>
>
>
> Sincerely,
>
> Dallas Maynard
> Applications Engineer
> Technical Support Group
>
> Sharp Microelectronics of the Americas
> 5700 NW Pacific Rim Blvd., M/S 20
> Camas, WA 98607
> 360-834-8067
> 360-834-8984 fax
> maynardd@sharpsec.com
>

---------------------------- snip
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Regards,

TomW

-- 
Tom Walsh - WN3L - Embedded Systems Consultant
'www.openhardware.net', 'www.cyberiansoftware.com'
"Windows? No thanks, I have work to do..."
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