On 12/25/2013 10:46 AM, Carl Denk wrote:
> The plug into auto's cigarette lighter plug/cord for my Lowrance
> I-finder color handheld GPS fried. Although the Internet search finds
> lots of vendors selling these, there is no stock, and no prospects of
> finding a replacement. I was able to open up the plug's case which
> contains a .55" (14mm) x 1.05" (26mm) PCB with a 34063A, 8-SOIC package
> switching regulator. First I made up a new board with a AS2954, TO-92
> package 250 ma linear regulator (readily available from a nearby
> supplier) , which borderline worked with the output voltage under load
> 2.5 volts, and blew the regulator once. Then, never had worked with
> surface mount before, tried to remove the SOIC chip using a heat gun
> from under side of the board, prying gently up on the chip. Was going
> good, but then 2 pads tore loose from the PCB. At this time, looking for
> a good solution with following thoughts:
> 1: Find a similar (3.3 VDC, 500ma) adapter off the shelf for a different
> unit, splice the cable
> 2: Build up a Through the hole board with a Rohm BA 33CC0FP linear
> regulator
> (http://www.digikey.com/product-search/en?vendor=3D0&keywords=3Dba33dd0t)=
..
> Overall power consumption not an issue, but heating of the plug with PCB
> inside is, but not thinking it's a concern. The plug is fused.
> 3: Build up a through the hole board with a switching regulator, but the
> design of these is out of my turf. I see examples of 5 volt applications
> in the data sheets, picture to adjust voltage, I would have to modify
> the voltage divider resistors to the comparator pin, but wouldn't know
> which inductor to select.
>
> Any suggestions and comments appreciated. :)
Have you searched ebay? Here is a downverter that takes 12v and switches=20
it to 3.3v @3A and it's ony $1.53...
http://www.ebay.com/itm/LED-Power-3A-12V-To-5V-3-3V-DC-DC-Converter-Buck-St=
ep-down-Module-Voltage-EP98-/131077033676?pt=3DLH_DefaultDomain_0&hash=3Dit=
em1e84cccecc
Dave
--=20
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