Power LED driver

[Marked]

"Measuring only 15 x 15 mm, the FX5959G701ADJ dc/dc converter claims to be not only the first complete constant-current-source module to include all necessary components in a single package, but also the industry's smallest complete power LED driver—enabling the design of highly compact lighting products. The part incorporates 20 components, requires no external components, and drives power LEDs rated for operation at or above 300 mA by simply being connected with the LED and a low-voltage source, such as a battery."
http://electronicproducts.com/ShowPage.asp?SECTION=3700&PRIMID=&FileName=hlcn5.oct2004.html

http://www.vishay.com/docs/10135/fx59g701.pdf

 

[NewBie]

Too bad it only fits in a 21.21mm (0.835163 inch) radius.

Odd, no efficiency charts.

Sure gets hot under load, maybe thats why they left the efficiency info off the sheet.

 

[HarryN]

Well Doug, for a commercial device, it is likely not as efficient as some of the ultra efficient parts you build.

At the same time, it is probably better than the resistors I end up using when I cannot fit in a board from georges80. Maybe if they get some feedback, they can shrink it until they build enough volume to come out in an IC version.

Maybe it is just me, but a BGA format is a larger challenge for a normal CPFr than the non optimal efficiency.

 

[LED_ASAP]

15x15mm isn't really that small. You can't even fit that into a minimag if you want to get 2xLiIon cells and a LuxIII or LuxV. For a "pseudo-IC" type of product, I really hope they can get something much smaller. It will be interesting to see what parts they use in the package, though /ubbthreads/images/graemlins/smile.gif

 

[Doug S]

[ QUOTE ]
NewBie said:
Too bad it only fits in a 21.21mm (0.835163 inch) radius.

Odd, no efficiency charts.

Sure gets hot under load, maybe thats why they left the efficiency info off the sheet.

[/ QUOTE ]
NewBie, like you, I find the lack of efficiency data odd, especially considering that they devote pages to graphs of more esoteric stuff like rise and fall times. What a sh*tty datasheet. /ubbthreads/images/graemlins/thumbsdown.gif We can infer though that efficiency isn't very good from their dropout voltage data. Stepdowns with 100% duty cycle capability are generally at their highest efficiency right at dropout. Their graphs show dropout voltages on the order of 0.5V. For a 3.3V output that would account for 0.5/(3.3+0.5)=13% loss minimum. It is goofy that they designed in a rather excessive loss by having a high drop across their Ro sense resistor.