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Path: ...!weretis.net!feeder9.news.weretis.net!usenet.blueworldhosting.com!diablo1.usenet.blueworldhosting.com!nnrp.usenet.blueworldhosting.com!.POSTED!not-for-mail From: "Edward Rawde" <invalid@invalid.invalid> Newsgroups: sci.electronics.design Subject: Re: more X-rays Silvertel PoE Supply Date: Wed, 2 Oct 2024 16:55:44 -0400 Organization: BWH Usenet Archive (https://usenet.blueworldhosting.com) Lines: 42 Message-ID: <vdkc0h$13ft$1@nnrp.usenet.blueworldhosting.com> References: <tipofjdtie76lbtd7lc2ger5uo7sglq3p5@4ax.com> <vdiorj$1l904$1@solani.org> <v6mqfjd93ib6q8j7d7ontsaouidieh5b2u@4ax.com> <vdjpse$n3s$1@nnrp.usenet.blueworldhosting.com> <vdjvmh$3aipj$1@dont-email.me> <vdk1rm$1o2a$1@nnrp.usenet.blueworldhosting.com> <nnd$7f138845$4f992b3a@6f6ac280155cacc4> <vdkani$g4m$1@nnrp.usenet.blueworldhosting.com> <nnd$750eb9bd$023dc468@2d1125609bcfdb68> Injection-Date: Wed, 2 Oct 2024 20:55:45 -0000 (UTC) Injection-Info: nnrp.usenet.blueworldhosting.com; logging-data="36349"; mail-complaints-to="usenet@blueworldhosting.com" Cancel-Lock: sha1:JXJACqB1p4tK24bFDzZqJBA9Jc4= sha256:h4NbkHm3tWYcfvKPls+O+hQ9veValfoQVeGVT9Wz1kA= sha1:zBItnxh/5P6n3h3/89WJXAiPF3E= sha256:gN70P59AvlqtfYnF5sGhqqj1ax5k7sPf+dnkI7Squlg= X-RFC2646: Format=Flowed; Response X-Newsreader: Microsoft Outlook Express 6.00.2900.5931 X-MSMail-Priority: Normal X-Priority: 3 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 Bytes: 3440 "Arie de Muijnck" <noreply@ademu.nl> wrote in message news:nnd$750eb9bd$023dc468@2d1125609bcfdb68... > On 2024-10-02 22:33, Edward Rawde wrote: >> "Arie de Muijnck" <noreply@ademu.nl> wrote in message news:nnd$7f138845$4f992b3a@6f6ac280155cacc4... >>> On 2024-10-02 20:02, Edward Rawde wrote: >>>> "Don Y" <blockedofcourse@foo.invalid> wrote in message news:vdjvmh$3aipj$1@dont-email.me... >>>>> On 10/2/2024 8:46 AM, Edward Rawde wrote: >>>>>> I did PoE with LTC4267 some years ago such that 12V could also be supplied from a wart. >>>>>> Fully isolated with a PA1138 transformer. >>>>> >>>>> How did you inform the PD of the fact that it was no longer >>>>> dependant on (and controllable by) the PSE? Or, did you forego >>>>> in-band reconfiguration and power control? >>>> >>>> It wasn't necessary for the fairly specialized product which was configured at install time with power from PoE or wart but not >>>> both. >>>> I seem to recall at least one accidental connection of both with no detrimental effect but it wasn't investigated further. >>> >>> >>> I've seen a problem when the PoE module had a TL431 + optocoupler at it's output as feedback circuit. >>> A limiting resistor was lacking, and +12.3V from a wart turned the TL431 fully on and destroyed the optocoupler. >>> Subsequent PoE operation then had an open loop and destroyed the supplied circuit. >> >> A seperate smaller schottky and capacitor for just the TLV431 seems to work fine in the LTC4267 simulation I just did and works >> around wall wart power getting connected to the TLV431. >> >> To disconnect wart power when PoE is operating, put a low power voltage doubler on the transformer secondary and use the 24V to >> swich off a p-fet in series with wart power. >> >>> >>> Arie >>> > > > Way too complex. A series resistor between TL431 and optocoupler was all that was needed. Only needed one BAT54 (a few cents) in my circuit. > > Arie >