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Maxim > Design Support > Technical Documents > Reference Designs > Medical > APP 5510

Maxim > Design Support > Technical Documents > Reference Designs > Power-Supply Circuits > APP 5510

Maxim > Design Support > Technical Documents > Reference Designs > Protection and Isolation > APP 5510

Keywords: power, pmod, industrial sensors, process control, industrial automation, medical, industrial power, halo

electronics, transformer, lakewood, maxrefdes7, industrial, dual supplies, power

REFERENCE DESIGN 5510 INCLUDES: Tested Circuit Schematic BOM Description Test Data Layout

Lakewood (MAXREFDES7#): 3.3V Input, ±12V (±15V)

Output Isolated Power Supply

Nov 06, 2012

Abstract:

This document

details the Lakewood (MAXREFDES7#) subsystem reference design, a 3.3V input, ±12V

(±15V) output, isolated power supply. The Lakewood reference design includes a 3W primary-side transformer H-

bridge driver for isolated supplies, and two wide input range and adjustable output low dropout (LDO) linear

regulators. Test results and hardware files are included.

Introduction

The Lakewood design (MAXREFDES7#) uses an H-bridge

transformer driver (MAX256) and a pair of low dropout (LDO)

linear regulators (MAX1659 x2) to create a ±12V (±15V)

output isolated power supply from a 3.3V voltage input

(Figure 1). This general-purpose power solution can be used

in many different types of isolated power applications, but is

mainly targeted for industrial sensors, industrial automation,

process control, and medical applications.

More detailed image (PDF, 1.9MB)

Figure 1. The Lakewood subsystem design block diagram.

Features Applications

Isolated power

±12V (±15V) outputs

Small printed circuit board (PCB) area

Pmod™-compatible form factor

Industrial sensors

Process control

Industrial automation

Medical

Detailed Description of Hardware

The Lakewood subsystem reference design operates from a 3.3V DC power source. The MAX256 H-bridge

transformer driver switches at approximately 475kHz and drives the primary side of the 1:2.6 turns ratio, with the

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Summary of content (5 pages)

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Maxim > Design Support > Technical Documents > Reference Designs > Medical > APP 5510 Maxim > Design Support > Technical Documents > Reference Designs > Power-Supply Circuits > APP 5510 Maxim > Design Support > Technical Documents > Reference Designs > Protection and Isolation > APP 5510 Keywords: power, pmod, industrial sensors, process control, industrial automation, medical, industrial power, halo electronics, transformer, lakewood, maxrefdes7, industrial, dual supplies, power REFERENCE DESIGN 5510 INCL
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use of a TGM-H281NF transformer from Halo® Electronics. The transformer secondary side is connected to voltage doublers that rectify the AC outputs into DC outputs. Two MAX1659 LDOs regulate the voltages to +12V and -12V, respectively. The Zener diodes (D3 and D6) protect the LDOs by keeping their input voltages below 16.1V. The input power can be from the J1 Pmod-compatible connector or from an external power supply connected to the EXT_+3.3V and DGND connectors.
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simultaneously. To achieve a larger maximum load, the user can either increase the input power supply voltage or increase the transformer turns ratio properly. Refer to the MAX256 data sheet for details. The power efficiencies are illustrated in Figure 2 and Figure 3. For asymmetrical voltage level applications, the maximum load can be larger for one rail and less for the other rail. Figure 2. Power efficiency vs. current load for ±12V outputs. Figure 3. Power efficiency vs. current load for ±15V outputs.
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Figure 6. Noise at VOUT = 12V, IOUT = 90mA. Figure 7. Noise at VOUT = 15V, IOUT = 40mA. All Design Files Hardware Files Schematic Bill of materials (BOM) PCB layout PCB Gerber PCB CAD (PADS 9.0) Buy Reference Design Lakewood (MAXREFDES7#) Halo is a registered trademark of Halo Electronics, Inc. Pmod is a trademark of Digilent Inc. Related Parts MAX1659 350mA, 16.
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