Return-Path: Received: from rly-ma09.mx.aol.com (rly-ma09.mail.aol.com [172.20.116.53]) by air-ma04.mail.aol.com (v121_r2.11) with ESMTP id MAILINMA043-8c848ad595f3b2; Thu, 21 Aug 2008 08:03:09 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-ma09.mx.aol.com (v121_r2.11) with ESMTP id MAILRELAYINMA092-8c848ad595f3b2; Thu, 21 Aug 2008 08:02:48 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1KW8rB-0004zf-HL for rs_out_1@blacksheep.org; Thu, 21 Aug 2008 13:01:37 +0100 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1KW8rB-0004zW-2h for rsgb_lf_group@blacksheep.org; Thu, 21 Aug 2008 13:01:37 +0100 Received: from smtp819.mail.ird.yahoo.com ([77.238.189.19]) by relay2.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1KW8r6-0005st-VT for rsgb_lf_group@blacksheep.org; Thu, 21 Aug 2008 13:01:36 +0100 Received: (qmail 8030 invoked from network); 21 Aug 2008 12:01:26 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=Received:X-YMail-OSG:X-Yahoo-Newman-Property:Received:Message-ID:From:To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=0hkhz5fWBLB6a75DlsSdk2P9kI4HD1euEePY/ZB3Cnu671hvfPc8uJfQuxm32SAsFkGfkVL1dGLEE3P2sKI2mIYzPkl3RXbeHWD6RBagkN/FQejUexunwUURR0YMmptH09MAhOw9lMeXYji82prYasKyH32EYpgdsdYyfYLmS44= ; Received: from unknown (HELO w4o8m9) (james.moritz@btopenworld.com@86.135.94.149 with login) by smtp819.mail.ird.yahoo.com with SMTP; 21 Aug 2008 12:01:25 -0000 X-YMail-OSG: v.UtRhAVM1lLExjK2BIWMhSZsabwZI7vItfvVlzjZ9GEqCnaL0pkbz.pwl_CxnJePTulN.MXd_FS6GS_nVkE87KMtSJOXd.XurkXuycPfYBpQ.OvaZ.mXuTk2V7s0Cxe.uU- X-Yahoo-Newman-Property: ymail-3 Received: from 127.0.0.1 (AVG SMTP 7.5.524 [270.6.6/1625]); Wed, 20 Aug 2008 20:56:04 +0100 Message-ID: <001101c902fe$c75bca00$4201a8c0@home> From: "James Moritz" To: Date: Wed, 20 Aug 2008 20:56:04 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 DomainKey-Status: good (testing) X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=disabled,DATE_IN_PAST_12_24=0.881 Subject: LF: 500kHz PA with IR2110 driver Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.4 required=5.0 tests=DATE_IN_PAST_12_24 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-IP: 193.82.116.20 X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_helo : n X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_822_from : n Dear Rik, LF Group, The IR2110 delivers only a little more gate drive than a TC4426/7. Recently I have been uprating my 10W EER transverter to 100W - driving the Mosfet gates is about 3.7 times more difficult at 500k compared to 137k :-) I find that the limiting factor on switching speed seems to be circuit strays rather than the gate driver itself. Trying to charge and discharge a Mosfet gate with the equivalent of some nF of capacitance in something of the order of 100ns isn't easy, and is quite sensitive to circuit layout, decoupling, grounding and so on. The voltage-switching type of class D seems to be a bit better at the higher frequency, partly because the drain current in the Mosfets is low around the switching point, which means somewhat slower switching transitions are OK. Also the drain-source voltages are somewhat lower at a given supply voltage, which lets you choose a lower voltage Mosfet with less gate capacitance. Cheers, Jim Moritz 73 de M0BMU