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User's Guide

SNVA667A–June 2012–Revised April 2013

AN-2239 LM5018 Isolated Evaluation Board

1 Introduction

An isolated bias supply is implemented in this evaluation board with LM5018 Constant-On-Time regulator.

LM5018 regulator integrates both the high and low side power switches essential for creating isolated

buck converter.

Board Specifications:

• Input Range: 20V to 100V

• Primary Output Voltage: 10V

• Secondary (Isolated) Output Voltage: 9.5V

• Maximum Load Current (Primary + Secondary): 250mA

• Maximum Power Output: 2.5W

• Nominal Switching Frequency: 750kHz

• Efficiency (FIN = 36V, IOUT2 = 250mA): 77 percent

• Board size: 2 inch × 2 inch

Figure 1. LM5018 Evaluation Board (Top View)

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SNVA667A–June 2012–Revised April 2013 AN-2239 LM5018 Isolated Evaluation Board

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Summary of content (7 pages)

PAGE 1
User's Guide SNVA667A – June 2012 – Revised April 2013 AN-2239 LM5018 Isolated Evaluation Board 1 Introduction An isolated bias supply is implemented in this evaluation board with LM5018 Constant-On-Time regulator. LM5018 regulator integrates both the high and low side power switches essential for creating isolated buck converter. Board Specifications: • Input Range: 20V to 100V • Primary Output Voltage: 10V • Secondary (Isolated) Output Voltage: 9.
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UVLO Threshold and Hysteresis 2 www.ti.com UVLO Threshold and Hysteresis The UVLO resistors are selected using the following two equations: VIN(HYS) = IHYSR1 (1) and VIN (UVLO,rising) = 1.225V x § R1 · +1 © R2 ¹ (2) On this evaluation board R1 = 127kΩ and R2 = 8.25kΩ, resulting in UVLO rising threshold at VIN = 20.5V and a hysteresis of 2.54V. 3 Board Connection and Start-Up The input connections are made using TP1 (VIN) and TP2 (GND) terminals.
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Bill of Materials www.ti.com 5 Bill of Materials Item Description Mfg., Part Number Package Value U1 Sync Switching Regulator Texas Instruments, LM5018 SO PowerPAD-8 100V, 300mA T1 Coupled Inductor, 1500 VDC Coilcraft, LPD5030V-473ME 5mm × 5mm 47uH, 0.47A Alternate Part Wurth, 750312750 8.26mm × 6.60mm 22uH, 0.76A D1 Schottky Diode Diodes Inc., DFLS1100-7 Pwr–DI123 100V, 1A D2 Schottky Diode Diodes Inc.
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Performance Curves 6 www.ti.com Performance Curves 100 EFFICIENCY (%) 90 VIN=36V VIN=24V 80 VIN=48V 70 60 VOUT2=10V, IOUT1=0 50 50 100 150 200 250 LOAD CURRENT (mA) 300 Figure 3. Efficiency at 750 kHz, VOUT1 = 10V Figure 4. Steady State Waveform (VIN = 48V, IOUT1 = 0mA, IOUT2 = 100mA) Figure 5.
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PC Board Layout www.ti.com 7 PC Board Layout Figure 6.
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PC Board Layout www.ti.com Figure 7. Board Top Layer Figure 8.
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