Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 735BD38000095; Tue, 9 Apr 2013 14:06:17 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UPcSU-0000dP-Eb for rs_out_1@blacksheep.org; Tue, 09 Apr 2013 18:35:50 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UPcST-0000dG-UM for rsgb_lf_group@blacksheep.org; Tue, 09 Apr 2013 18:35:49 +0100 Received: from mail-oa0-f51.google.com ([209.85.219.51]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1UPcSS-0004fI-3b for rsgb_lf_group@blacksheep.org; Tue, 09 Apr 2013 18:35:48 +0100 Received: by mail-oa0-f51.google.com with SMTP id g12so7652099oah.24 for ; Tue, 09 Apr 2013 10:35:25 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=CW57+cxbk1hppc0v+v5p9K8BXYABvocWAwWoulHVCvY=; b=tissVLKZx7mEI/fgwQMsu3feiEj/GDxq+BU92GAx4oR3Qkze+VPocuDoZcGkqrz6jY 6/r5nuDQnNIq1ItipfYbzdit71Q28/VmP0+N/+d4upMBgVH2z5HAGAsNPOqvKOAbtkre xjmssffyawGC/9SzKx4LBJMlOs+7iqBAY0GNz3eGDh97LNRY5UsZUQ+ZZklUNmMH3gLb s2iWqqDPYHx9D+xYzJIbQizRSzU8NAk5E1tFvPhNF1ocHC3wEM+iOs54VycDgZtZtKjs xcrRanQABORkgedIL7zTdIzla58Ex9e78hhUvaM698MDvDSnMia4mG54IPF18fBen/2Y yyIg== MIME-Version: 1.0 X-Received: by 10.60.62.70 with SMTP id w6mr19726979oer.38.1365528925763; Tue, 09 Apr 2013 10:35:25 -0700 (PDT) Received: by 10.60.135.199 with HTTP; Tue, 9 Apr 2013 10:35:25 -0700 (PDT) In-Reply-To: <516436CC.1090606@iup.uni-heidelberg.de> References: <5164092A.3090803@iup.uni-heidelberg.de> <516436CC.1090606@iup.uni-heidelberg.de> Date: Tue, 9 Apr 2013 13:35:25 -0400 Message-ID: From: Warren Ziegler To: rsgb_lf_group X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: 30 milliohm On Tue, Apr 9, 2013 at 11:42 AM, Stefan Schäfer < wrote: > ** > Hi Warren, > > What is the value of the shunt resistor? > > 73, Stefan > > Am 09.04.2013 17:00, schrieb Warren Ziegler: > > Hi Stefan, > > I think you are advocating higher voltage and lower current to > decrease loss in the FET due to the on resistance which is a good idea. > > But what I am looking for is for over-current protection which would > be valuable in any class-D design regardless of the choice of FETs. As Alan > has pointed out the wrong output impedance can cause the amp to draw large > currents. I am now using a current sense resistor but I was thinking that > Hall Effect might be more efficient. > > 73 Warren > > > > On Tue, Apr 9, 2013 at 8:27 AM, Stefan Schäfer < > wrote: > >> Hi Warren, >> >> Instead of spending to much effort to the current sensing my advice is to >> use other FETs. A 500 V FET at 30 V supply voltage is a heavy waste of >> power in the on resistance. For 30 V and a class D, try e.g. a IRFP3710or >> IRFP150N. That should work much better. >> >> 73, Stefan/DK7FC >> > [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.219.51 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (wd2xgj[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: e2fb1a5df1e2bc3146a6f486b4640b03 Subject: Re: LF: Re: Hall Effect for Over-current shutdown? Content-Type: multipart/alternative; boundary=089e01294f308d021904d9f0fa75 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-da02.r1000.mx.aol.com ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d404a516458992b1a X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --089e01294f308d021904d9f0fa75 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 30 milliohm On Tue, Apr 9, 2013 at 11:42 AM, Stefan Sch=E4fer < Stefan.Schaefer@iup.uni-heidelberg.de> wrote: > ** > Hi Warren, > > What is the value of the shunt resistor? > > 73, Stefan > > Am 09.04.2013 17:00, schrieb Warren Ziegler: > > Hi Stefan, > > I think you are advocating higher voltage and lower current to > decrease loss in the FET due to the on resistance which is a good idea. > > But what I am looking for is for over-current protection which would > be valuable in any class-D design regardless of the choice of FETs. As Al= an > has pointed out the wrong output impedance can cause the amp to draw larg= e > currents. I am now using a current sense resistor but I was thinking that > Hall Effect might be more efficient. > > 73 Warren > > > > On Tue, Apr 9, 2013 at 8:27 AM, Stefan Sch=E4fer < > Stefan.Schaefer@iup.uni-heidelberg.de> wrote: > >> Hi Warren, >> >> Instead of spending to much effort to the current sensing my advice is t= o >> use other FETs. A 500 V FET at 30 V supply voltage is a heavy waste of >> power in the on resistance. For 30 V and a class D, try e.g. a IRFP3710<= https://dl.dropbox.com/u/19882028/Datenbl%C3%A4tter/irfp3710.pdf>or >> IRFP150N. That should work much better. >> >> 73, Stefan/DK7FC >> > --=20 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1 --089e01294f308d021904d9f0fa75 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
30 milliohm


On Tue, Apr 9, 2013 at 11:42 AM, Stefan Sch=E4fer <Stefan.Schaefer@iup.uni-heidelberg.de> wrot= e:
=20
Hi Warren,

What is the value of the shunt resistor?

73, Stefan

Am 09.04.2013 17:00, schrieb Warren Ziegler:
Hi Stefan,

=A0 =A0 =A0I think you are advocating higher voltage and lower current to decrease loss in the FET due to the on resistance which is a good idea.

But =A0what I am looking for is for =A0over-current protection which would be valuable in any class-D design regardless of the choice of FETs. As Alan has pointed out the wrong output impedance can cause the amp to draw large currents. I am now using a current sense resistor but I was thinking that Hall Effect might be more efficient.

73 Warren



On Tue, Apr 9, 2013 at 8:27 AM, Stefan Sch=E4fer <Stefan.Schaefer@iup.uni-heidelberg.de&g= t; wrote:
Hi Warren,

Instead of spending to much effort to the current sensing my advice is to use other FETs. A 500 V FET at 30 V supply voltage is a heavy waste of power in the on resistance. For 30 V and a class D, try e.g. a IRFP3710 or IRFP150N . That should work much better.

73, Stefan/DK7FC



--
73 Warren K2= ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 =A0 =A0 =A0 = =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
=A0 =A0 = =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0
--089e01294f308d021904d9f0fa75--