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    The PSU FAQ

    Using ATX and similar power supplies (P/Ss) as a pattern, P/Ss can be described as having seven sections: AC Filter; Rectifier & Filter; Inverter; Pulse Width Modulator; Output Rectifier & Filter; Voltage Sense Amplifier and Protection; Standby Regulator.

    AC Filter
    The AC filter is a network of inductors and capacitors on the “primary” side of the P/S intended to reduce the amount of noise conducted back into the AC power lines (can't be interfering with those TV and radio commercials). Capacitors connected from Line to Neutral (X capacitors) and single-winding inductors reduce noise that is on Line with respect to Neutral. Capacitors connected from Line and Neutral to chassis ground (Y capacitors) and two-winding inductors reduce noise that is common to Line and Neutral with respect to chassis ground. X and Y capacitors are special types that have approval marks from various countries' safety agencies. These should not be replaced with general purpose types. Y capacitors are always in pairs, and if replaced, the same value should be used.

    Rectifier & Filter
    The rectifier and filter convert the AC input voltage to DC. The input voltage selector switch is part of this circuit. In the “115V” position, the rectifier circuit is configured as a voltage doubler. In the “230V” position, the rectifier circuit is configured as a full wave bridge. In either case, the unregulated high voltage bus is about 300VDC. If the switch is in the “115V” position in Europe, the metal oxide varistors (MOVs) in parallel with the two input electrolytic capacitors will fire, blowing the fuse. If the MOVs fail (usually blowing up) before the fuse blows, the two input electrolytic capacitors, usually rated 250V, will vent. If the P/S is operated in the US with the switch in the “230V” position, the P/S may seem to operate OK in a system that isn't fully loaded. In a fully loaded system the P/S may not operate, or it may perform erratically. Either way, the P/S will run hotter and its life may be reduced.

    Inverter
    This is the heart of a switching power supply. The inverter converts the 300VDC into a square wave of varying duty cycle . The positive part of the square wave across the transformer primary (and the secondary windings, except for the -12V and -5V secondary winding) corresponds to the time when the switch device (now usually a MOSFET) is on. The transformer steps the 300Vp-p square wave down to the appropriate voltage levels.

    Pulse Width Modulator
    The output voltage of a switching power supply, after the output rectifier and filter, approximately equals the duty cycle times the peak voltage of the square wave. Since the 300VDC bus is unregulated, that peak voltage varies with the AC input voltage. Regulation of the output voltage is achieved by controlling the duty cycle of the square wave. This is done by the pulse width modulator, which compares the output voltage (indirectly) to a sawtooth voltage to determine the width of each positive output pulse. In some designs, the sawtooth voltage is a sample of the transformer primary current, which is converted to a voltage by a low value resistor between the switch MOSFET Source and primary return.

    Output Rectifier & Filter
    Though the output rectifiers are usually two rectifiers in one package, in the most common topology, the two devices have different functions. One of the devices conducts during the “on” part of the square wave from the transformer, charging the inductor. The other rectifier conducts during the “off” time, providing a current path for the discharge of the inductor. The output inductor and output capacitors form a filter that convert the square wave to a DC voltage. The current through the inductor has two components - the current to the load, and the charging-discharging current super-imposed. The current through the filter capacitor(s) is the inductor charging-discharging current plus some transient currents due to large changes in the load current. Since the ripple current through the capacitor(s) can be several amps rms, low impedance capacitors are absolutely essential. This side of the P/S is commonly referred to as the “secondary” side.

    Voltage Sense Amplifier and Protection
    Here is the control center of the power supply. The main feedback circuit senses the +5V output and often the +12V output as well. The +3.3V output is usually mag-amp (magnetic amplifier) post-regulated. The -12V and -5V outputs are usually post-regulated with three-terminal linear regulators (Mac doesn't use a -5V output). P/Ss also typically have circuits that monitor the +5V, +3.3V, and +12V outputs going out of regulation high. If this occurs, the circuit will latch the P/S off (cycling AC power will clear the latch condition, but if the problem cause is still present, the P/S will latch off again). There may be circuits that sense the output currents for the +5V, +3.3V, and +12V outputs that will limit the current on the output(s) and reduce the output voltages of those outputs. Many P/Ss have a temperature sensor located on the heatsink for the output rectifiers (this is usually expected to be the hottest spot). This sensor connects to a circuit that will turn off or latch off the P/S if the temperature exceeds a preset threshold. In some P/Ss, the output voltage sense amplifier and protection circuits are integrated into a custom IC.

    Standby Regulator
    The Standby Regulator is a separate, low power, P/S. Unlike the main P/S, it is active almost immediately after plugging in the power cord. Depending on the current rating, this circuit may be a self-oscillating inverter with a 3-terminal linear post-regulator or a higher current switching regulator. This circuit powers power management circuitry on the computer motherboard (including the on/off function), as well as secondary-side protection circuits (e.g. latch-off protection functions).
    Last edited by willawake; 01-01-2006, 01:15 PM.
    PeteS in CA

    Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
    ****************************
    To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
    ****************************

    #2
    Re: The PSU FAQ

    reserved
    capacitor lab yachtmati techmati

    Comment


      #3
      Re: The PSU FAQ

      reserved 2
      capacitor lab yachtmati techmati

      Comment


        #4
        PSU Company Links

        PSU Company Links

        Acbel Polytech http://www.acbel.com/
        Addtronics http://www.addtronics.com/ (Enhance)
        Aerocool http://www.aerocool.com.tw/
        Akasa http://www.akasa.com.tw/ (Enhance)
        Alpha Power http://www.alphapower.us
        AMS http://www.amselectronics.com
        Antec http://www.antec.com/
        AOpen http://www.aopen.com/
        Apex Tech (Allied) http://www.apextechusa.com/
        Aspire http://www.aspireusa.net/
        Athena Power http://www.athenapower.com/
        Asus http://www.asus.com/
        Atadc http://www.atadc.com/
        Atng Power Co. / I Horng Power Co. http://www.atngpower.com.tw/
        Atrix http://www.atrixcase.com/
        Channel Well Technology http://www.cwt.com.tw/ (OEM)
        Chieftec http://www.chieftec.com/ (Highpower, Acbel?)
        CHS Plus http://www.chsay.com.tw/
        Codegen Group http://www.codegengroup.com/
        Cooler Master http://www.coolermaster.com/
        CoolMax http://www.coolmaxusa.com/
        Deer Computer Co. Ltd. / Allied, L&C, Austin http://www.deer-group.com/
        Delta Electronics http://www.delta.com.tw
        Delux Technology / Shenzen Delux http://www.deluxworld.com/
        Donguan Sunter http://www.dgsunter.com
        Dynapower USA http://www.dynapowerusa.com/
        Eagle Technology http://www.skyhawkusa.com/
        Elan Vital http://www.elanvital.com.tw
        Enermax Technology Corp http://www.enermax.com.tw/
        Enhance http://www.enhance.com.tw/ (OEM)
        ENlight http://www.enlightcorp.com/
        Epower Technology http://epowertec.com/
        Etasis Electronics http://www.etasis.com.tw/
        Eurocase http://www.eurocase.cz/
        Fortron / Source http://www.fsusa.com/
        Fran Mar http://www.franmar.com.tw
        FSP Group (Fortron Headquarters) http://www.fsp-group.com.tw/ (OEM)
        Global WIN Technology http://www.globalwin.com.tw/
        HEC Computer (Herolchi) http://www.hec-group.com.tw/ (OEM)
        Hedy http://www.hedy.com.cn
        High Power http://www.highpowersupply.com/ (OEM)
        Hiper http://www.hipergroup.com
        HIPro http://www.hipro.com.tw/
        Huadian http://www.hd-power.com/
        Huntkey http://www.huntkey.com/
        ICP America http://www.icpamerica.com
        In Win http://www.in-win.com.tw
        JJC Power http://www.jjcchina.cn
        Jou Jye http://www.jj-computer.com/
        Just PC Inc. http://www.justpcusa.com/
        Key Mouse (KME) http://www.kmepc.com/
        Kex Tech http://www.kextech.com
        King Pro http://www.kingpropower.com
        Leadman http://www.leadman.com.tw/
        Levicom http://www.levicom.de
        Linkworld Electronic Co. http://www.linkworld.com.tw
        Macron Power (Casing Macron Technology) http://www.casing.com.tw/ (OEM)
        Meiji / Leadway http://www.meijipower.com
        MGE Company http://www.mgecompany.com
        Nexus http://www.nexustek.nl/
        OCZ Technology http://www.ocztechnology.com/ (Fortron)
        Panstar Electronics http://www.panstar.com
        PC Power and Cooling http://www.pcpowerandcooling.com
        Powertech (Division of FSP) http://www.powrtech.com/
        Power Win http://www.power-win.com/
        Powmax http://www.powmax.com/
        Q-tec http://www.qtec.info/
        R-Senda http://www.rsenda.com/
        Raidmax http://www.buyraidmax.com
        Rosewill http://www.rosewill.com/
        Seasonic Electronics http://www.seasonic.com
        Seventeam http://www.seventeam.com.tw/
        Silenx http://www.silenx.com/
        Silverstone Technology http://www.silverstonetek.com/ (Enhance)
        SinTek http://www.sin-tek.com/
        Sparkle Power Inc. http://www.sparklepower.com
        Sunbeamtech http://www.sunbeamtech.com/
        Sunpower http://www.sunpower-usa.com
        Super Flower http://www.super-flower.com.tw/
        Supermicro http://www.supermicro.com/
        Superpower http://www.superpower.com/
        Suppower http://www.suppower.com/
        Tagan http://www.tagan.de/
        Task International http://www.task.com.tw/
        Thermaltake http://www.thermaltake.com/
        TomMade http://www.tommade.com
        Topower http://www.topower.com.tw
        Topmay http://www.topmay-computer.com
        Top Microsystems http://www.topmicro.com
        Tri-Mag http://www.tri-mag.com/
        Ultra Products http://www.ultraproducts.com/ (Wintech, Young Year)
        Vantec http://www.vantec.com.tw/
        Verudium http://www.verudium.com/
        Wintech Electronics http://www.wintech-corp.com.tw/ (OEM)
        Worldcom Asia http://www.worldcomasia.com/
        Win-Tact http://www.win-tact.com.tw/
        Xilence (Levicom) http://www.xilencepower.com/
        Xion http://www.xionusa.com
        Yilan / Goosen / Ever Lastin http://www.yilangz.com
        Zalman http://www.zalman.co.kr/
        Zhongchang http://www.zhongchang.biz
        Zippy Technology http://www.zippy.com.tw

        This is meant to be a comprehensive list and is not a recommendation of these companies by badcaps.net
        Last edited by willawake; 01-26-2006, 05:14 PM.
        capacitor lab yachtmati techmati

        Comment


          #5
          Re: The PSU FAQ

          PSU Reference Material

          Here is a reference design from On Semi (formerly Motorola) for a 250W ATX PSU with 80% efficiency:

          https://www.onsemi.com/PowerSolution...ent.do?id=1331

          Included is a 35-page design guide that includes circuit board patterns.

          Lots of links to FAQs and schematics of ATX PSUs:

          www.smps.us/computer-power-supply.html

          200W DTK ATX PSU schematic and description:

          www.pavouk.comp.cz/hw/en_atxps.html

          Information about System General SG6105 PSU controller chip:




          A schematic of an InWin 300W PSU:

          http://narod.yandex.ru/100.xhtml?sp...ma/iwp300a2.gif
          (thanks larrymoencurly)
          Last edited by willawake; 01-01-2006, 01:23 PM.
          capacitor lab yachtmati techmati

          Comment


            #6
            Re: The PSU FAQ

            yes it is a work in progress. please contribute whatever sections you like to
            https://www.badcaps.net/forum/showthread.php?t=836

            and i will assemble it.
            capacitor lab yachtmati techmati

            Comment


              #7
              Re: The PSU FAQ

              Here are a couple more P/S mfrs: Astec; Phihong. I don't think either are players in the PC P/S market, but they are in adapters, servers/storage, and TV set-top devices.
              PeteS in CA

              Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
              ****************************
              To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
              ****************************

              Comment


                #8
                Re: The PSU FAQ

                I have 1997 Astec 145W ATX PSU.

                Comment


                  #9
                  Re: The PSU FAQ

                  willawake here is one
                  http://www.atngpower.com.tw/ OEM
                  they make the power supplies for rosewill and others

                  highly efficient power supplies:
                  http://www.80plus.org/suppliers.html
                  all are over 80% efficiect

                  Comment


                    #10
                    Re: The PSU FAQ

                    Pentium II power supplies: too young to smoke
                    http://www.edn.com/article/CA56651.html

                    http://www.powermanagementdesignline.com/
                    Last edited by willawake; 01-06-2006, 08:22 AM.
                    capacitor lab yachtmati techmati

                    Comment


                      #11
                      Re: The PSU FAQ

                      A short list of who makes what PSU- http://club.cdfreaks.com/showthread.php?t=130148
                      Ludicrous gibs!

                      Comment


                        #12
                        Re: The PSU FAQ

                        thanx guys keep em coming
                        capacitor lab yachtmati techmati

                        Comment


                          #13
                          Re: The PSU FAQ

                          Recently installed Delux PSU. Do not see on the list

                          url: http://delux.manufacturer.globalsour...page_num-1.htm
                          Gigabyte EP45-DS3L Ultra Reliable (Power saver)
                          Intel E8400 (3000Mhz) Bios temps. 4096Mb 800Mhz DDR2 Corsair XMS2 4-4-4-12
                          160Gb WD SATAII Server grade
                          Nvidia 8500GT 256Mb
                          160Gb WD eSATAII Server grade for backup.
                          Samsung 18x DVD writer
                          Pioneer 16x DVD writer + 6x Dual layer
                          33 way card reader
                          Windows XP Pro SP3
                          Thermaltake Matrix case with 430W Silent Power
                          17" Benq FP737s LCD monitor
                          HP Officejet Pro K5300 with refillable tanks

                          Comment


                            #14
                            Re: The PSU FAQ

                            How about LiteOn? Both of my brothers own LiteOn power supplies, and they've been going strong for 5/6 years now with no problems whatsoever. They seem to make only for OEMs though.

                            http://www.liteon.com
                            The ever-amazing (and ever-affordable) KY, Chemi-con's best kept secret.

                            I'll probably be the only person going to SteamOS once it gets out of beta (ha ha.)

                            Comment


                              #15
                              Re: The PSU FAQ

                              LiteOn is actually one of the top five or so PSU makers in the world, and their stuff is really well made. Attached is a photo of an old 300W model -- very crowded inside (no active PFC, despite only one large high voltage capacitor).
                              Attached Files
                              Last edited by larrymoencurly; 01-23-2006, 04:15 PM.

                              Comment


                                #16
                                Re: The PSU FAQ

                                i was going to add liteon before but no psu info on their site
                                capacitor lab yachtmati techmati

                                Comment


                                  #17
                                  Re: The PSU FAQ

                                  Originally posted by larrymoencurly
                                  LiteOn is actually one of the top five or so PSU makers in the world, and their stuff is really well made. Attached is a photo of an old 300W model -- very crowded inside (no active PFC, despite only one large high voltage capacitor).
                                  A lot of Dell PSU's are Lite-On too.

                                  What's ironic is that Dell buys them from Foxconn.

                                  Apparently, Foxconn was willing to pony up the $10K submission fee and consider it an investment (no doubt they got their return) and Lite-On didn't. And apparently, Foxconn didn't have enough faith in their own Deer product to pony up $10K and risk Dell denying certification for use in Dell machines.
                                  Rest in peace BFG. You were... a job...

                                  Comment


                                    #18
                                    Re: The PSU FAQ

                                    PCMCIS- Topower
                                    PC Power & Cooling- FSP Group
                                    Powerman- FSP Group
                                    Powmax- Ultra

                                    taken from a short list of who makes PSU`s...

                                    I didn`t know that FSP Group made PC Power & Cooling PSU`s....hmmmmm

                                    Comment


                                      #19
                                      Re: The PSU FAQ

                                      Powmax is Powmax. Have always been. Ultra is Wintech or Young Year. PCP&C's TurboCool line are made by Win-Tact. Powerman is indeed FSP.
                                      The great capacitor showdown!

                                      Comment


                                        #20
                                        Re: The PSU FAQ

                                        Originally posted by Chris1992
                                        Powmax is Powmax. Have always been.
                                        Yes indeed - although, if I'm not mistaken, Powmax is a "daughter" company of sorts of Leadman, which markets those same (inglorious) Powmax PSUs under a number of other generic-sounding names.

                                        I recall that kc8adu posted a photo only a few weeks ago in the "PSU Pictorial" thread, in which one such Leadman-Powmax PSU was even rebranded as "MGE Vigor".

                                        ...

                                        PS. I've never heard of any Ultra-branded units being Leadmax/Powmax's in disguise.
                                        Last edited by tiresias; 04-12-2006, 01:08 PM.

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