Received: from PCH.mit.edu (18.7.21.50) by mail.efplus.com (192.168.0.8) with Microsoft SMTP Server (TLS) id 8.3.485.1; Tue, 13 Oct 2020 04:07:31 -0700 Received: from PCH.MIT.EDU (localhost.localdomain [127.0.0.1]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 09DAvDZ9022444; Tue, 13 Oct 2020 06:57:55 -0400 Received: from outgoing-exchange-1.mit.edu (OUTGOING-EXCHANGE-1.MIT.EDU [18.9.28.15]) by PCH.mit.edu (8.14.7/8.12.8) with ESMTP id 09DAvAAN022422 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Tue, 13 Oct 2020 06:57:10 -0400 Received: from oc11exedge2.exchange.mit.edu (OC11EXEDGE2.EXCHANGE.MIT.EDU [18.9.3.18]) by outgoing-exchange-1.mit.edu (8.14.7/8.12.4) with ESMTP id 09DAv56O007766 for ; Tue, 13 Oct 2020 06:57:10 -0400 Received: from w92expo32.exchange.mit.edu (18.7.74.44) by oc11exedge2.exchange.mit.edu (18.9.3.18) with Microsoft SMTP Server (TLS) id 15.0.1293.2; Tue, 13 Oct 2020 06:56:37 -0400 Received: from oc11exhyb1.exchange.mit.edu (18.9.1.60) by w92expo32.exchange.mit.edu (18.7.74.44) with Microsoft SMTP Server (TLS) id 15.0.1365.1; Tue, 13 Oct 2020 06:57:08 -0400 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (104.47.59.173) by oc11exhyb1.exchange.mit.edu (18.9.1.60) with Microsoft SMTP Server (TLS) id 15.0.1395.4 via Frontend Transport; Tue, 13 Oct 2020 06:57:07 -0400 Received: from MWHPR14CA0008.namprd14.prod.outlook.com (2603:10b6:300:ae::18) by SN6PR01MB4958.prod.exchangelabs.com (2603:10b6:805:c1::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3455.24; Tue, 13 Oct 2020 10:57:05 +0000 Received: from CO1NAM03FT028.eop-NAM03.prod.protection.outlook.com (2603:10b6:300:ae:cafe::6) by MWHPR14CA0008.outlook.office365.com (2603:10b6:300:ae::18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3433.34 via Frontend Transport; Tue, 13 Oct 2020 10:57:05 +0000 Received: from mail-ej1-f46.google.com (209.85.218.46) by CO1NAM03FT028.mail.protection.outlook.com (10.152.80.189) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3455.23 via Frontend Transport; Tue, 13 Oct 2020 10:57:04 +0000 Received: by mail-ej1-f46.google.com with SMTP id qp15so27609131ejb.3 for ; Tue, 13 Oct 2020 03:57:04 -0700 (PDT) From: RussellMc To: Microcontroller discussion list - Public. CC: "Reid, John (Oji Fibre Solutions)" , ApptechNZ , "ken@elecsyn.com" Sender: "piclist-bounces@mit.edu" Date: Tue, 13 Oct 2020 03:56:25 -0700 Subject: [EE]:: Use of step down switching regulator for a negative supply Thread-Topic: [EE]:: Use of step down switching regulator for a negative supply Thread-Index: AdahUQv0NI6mpGC0RDWbEGrFYqRx5w== Message-ID: List-Help: List-Subscribe: , List-Unsubscribe: , Reply-To: Microcontroller discussion list - Public. Accept-Language: en-US X-MS-Exchange-Organization-AuthAs: Anonymous X-MS-Exchange-Organization-AuthSource: TS500.efplus4.local X-MS-Has-Attach: X-Auto-Response-Suppress: All X-MS-Exchange-Organization-SenderIdResult: Pass X-MS-Exchange-Organization-PRD: mit.edu X-MS-TNEF-Correlator: received-spf: Pass (protection.outlook.com: domain of gmail.com designates 209.85.218.46 as permitted sender) receiver=protection.outlook.com; client-ip=209.85.218.46; helo=mail-ej1-f46.google.com; dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=jh0dr50l/1IRB3mR2/GDscGVth2bZjAoKVv3428HASQ=; b=axqabT8gaRNnaR0qWPYKRt6ySHjqwVyZb84gwa8X5vUnXBKYmxETIxcKkvcKZNGivL svIgoGQ+S58MtH2H3OiGvodDI0rskgF+Fd+QGwH+aDsUiA9deG2JsjCCxhqIqCcvIJej rwf6N1o5DQnduHQcQQzzNM9lxwbJFYYPTO5ILL2Kd7994hJViUPRb+P6/uMICVyzD9rU iytYrY2SuLOdSej6oJs+z8Zf8AHk3p3AbsWm59hfNA/LsqFcOYEqPiCO0uL0I2v8pGFm HgEMZtWdk5wt0dHccvL3RVCGxtQRqg60QUjZUjHiruRgY8sn0IyPv0rAbEJ2vHtjC5Na LBeQ== authentication-results: spf=pass (sender IP is 209.85.218.46) smtp.mailfrom=gmail.com; mit.edu; dkim=pass (signature was verified) header.d=gmail.com; mit.edu; dmarc=pass action=none header.from=gmail.com; errors-to: piclist-bounces@mit.edu list-id: "Microcontroller discussion list - Public." list-post: x-beenthere: piclist@mit.edu x-mailman-version: 2.1.6 x-received: by 2002:a17:906:b204:: with SMTP id p4mr33495579ejz.214.1602586622612; Tue, 13 Oct 2020 03:57:02 -0700 (PDT) x-topics: [EE] x-content-filtered-by: Mailman/MimeDel 2.1.6 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 While this is obvious enough in retrospect, it's not something I recall having seen being done. An LM2576 buck converter IC is here used to provide a positive to negative conversion by grounding the positive output and bootstrapping the ground pin -vely to become the negative output. The method imposes some performance limitations but should be useful Section 8.1.9 pages 18-19 https://www.ti.com/lit/ds/symlink/lm2576.pdf?ts=3D1602318033185&ref_url=3Dh= ttps%253A%252F%252Fwww.google.com%252F SE EE Q*A using this method: https://electronics.stackexchange.com/questions/525680/lm2576-adj-bipolar-p= ower-supply-troubleshooting/525683#comment1355157_525683 Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .