Unfamiliar PWM IC.

[Pimpom]

I haven't closely examined many different computer PSUs. The ones
I've taken apart are mostly cheap Chinese ones and they're all
closely similar. Most of them use a TL494 or an SG3525 as the PWM
controller. Today, I happened to look at an old ATX PSU PCB which
uses a chip I'm not familiar with. The number is LPG-899 and it
has "Linkworld" printed in cursive font. The logo is a filled
triangle with a globe inserted half way on one side. Curious, I
searched for a datasheet but couldn't find one. That made me even
more curious and I kept on searching for some time, without
success.

It's in a 16-pin DIP package but the pin-outs are different from
the ones I know about. The push-pull outputs are taken from pin 7
and 8, driving two C945 transistors (Japanese low-power NPNs)
which in turn drive the output transistors.. The +5V output of
the PSU is fed back directly to pin 2, so this looks like Vcc.
The +12V output is goes via a resistive voltage divider to pin 3.
Pin 5 is grounded. I didn't check the rest. Is anyone familiar
with this IC?

 

[Martin Riddle]

I haven't closely examined many different computer PSUs. The ones I've
taken apart are mostly cheap Chinese ones and they're all closely
similar. Most of them use a TL494 or an SG3525 as the PWM controller.
Today, I happened to look at an old ATX PSU PCB which uses a chip I'm
not familiar with. The number is LPG-899 and it has "Linkworld"
printed in cursive font. The logo is a filled triangle with a globe
inserted half way on one side. Curious, I searched for a datasheet but
couldn't find one. That made me even more curious and I kept on
searching for some time, without success.

It's in a 16-pin DIP package but the pin-outs are different from the
ones I know about. The push-pull outputs are taken from pin 7 and 8,
driving two C945 transistors (Japanese low-power NPNs) which in turn
drive the output transistors.. The +5V output of the PSU is fed back
directly to pin 2, so this looks like Vcc. The +12V output is goes via
a resistive voltage divider to pin 3. Pin 5 is grounded. I didn't
check the rest. Is anyone familiar with this IC?

Seems to be similar to the 494. but a Chinese custom IC.
See this link
<http://translate.google.com/transla...en&safe=off&rls=com.microsoft:en-us&prmd=ivns>

Or use Google and search for "LPG-899 pwm", look for the YoReparo
spanish link and translate

Cheers

 

[Pimpom]

Seems to be similar to the 494. but a Chinese custom IC.
See this link
<http://translate.google.com/transla...en&safe=off&rls=com.microsoft:en-us&prmd=ivns>

Or use Google and search for "LPG-899 pwm", look for the
YoReparo
spanish link and translate

Cheers

Thanks. And sorry about the very late reply.

I had some trouble with the site but managed to get it. The
WT7520 mentioned on the site also looks very closely similar to
the LPG-899 except that the timing element at pin 6 is a resistor
while the LPG-899 uses a capacitor.