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In Reply to: RE: Linear 1.85v to DDRII for G31M-S2L posted by jackwong96 on January 19, 2011 at 08:25:24
Jack , I did remove " L" , same consumption on +5.0 v MoBo.
Could you please take look on picture and comment on purpose of ( ? K3918 ) , for
me, look like, it connected in opposite direction.
Thanks, Gene.
Follow Ups:
Hi Gene,
The PWM controller (the small IC on the downside of 2R0 ) does not provide enough current, so a set of MOSFET driver (K3918s on your MB) is required. Each power phase uses a driver IC, two MOSFETs and one choke (2R0 in this case).
You are pretty much done by cutting both the legs of the K3918s and desoldering 2R0. The current consumption should be a liitle bit more than before, as linear regulators are less efficient than swtiching ones. Note that it may need to supply current to the RAM and other components.
I believe the problem you've got may lies with (a) improper grounding connection for LT1083, and/or (b) inappropriate input point taken from the MB.
(a) You have two ground connections, one would suffice, better still the ground of the LT1083 should be connected to the main ground of the ATX port of the MB.
(b) I'm not sure the input of the LT1083 is correctly connected on the circuit you provided. For me, I would connect the input to the ATX 5V (or 3.3V for less heat disspation), or use a seperate linear power supply for better isolation.
You may try to lower the supply voltage to 1.8V or below for better SQ.
Good luck with your attempts.
Jack
Hi Jack,
Thanks for yours schematic and explanation .
Total power consumption on 5 volt MoBo line , did increase actually on power
dissipation on LT1083 - 6 WA , 3 volt between in -out needed for LT1083 for good
performance . In my cMP 3.3 volt line feeded by small battery , so I need feed
from 5 volt.
Will try take from MoBo 5 volt , and reduce to 1.75 v .
Still waiting for delivery rest of LT1083 !
Gene.
Jack I appreciate that you are probably busy and can't post here all the time and you probably get a lot of queries on pc stuff but I really learn a lot when I read your posts. Are there any other forums on which you post so one can follow your various projects?
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