Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsDev KitsPCB design board

User's Guide

SNVA675A–August 2012–Revised April 2013

AN-2284 LM34926 Isolated Evaluation Board

1 Introduction

An isolated bias supply is implemented in this evaluation board with LM34926 Constant-On-Time

regulator. LM34926 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 x 2 inch

Figure 1. LM34926 Evaluation Board (Top View)

All trademarks are the property of their respective owners.

SNVA675A–August 2012–Revised April 2013 AN-2284 LM34926 Isolated Evaluation Board

Submit Documentation Feedback

Summary of content (8 pages)

PAGE 1
User's Guide SNVA675A – August 2012 – Revised April 2013 AN-2284 LM34926 Isolated Evaluation Board 1 Introduction An isolated bias supply is implemented in this evaluation board with LM34926 Constant-On-Time regulator. LM34926 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.
PAGE 2
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. 2.1 Board Connection and Start-up The input connections are made using TP1 (VIN) and TP2 (GND) terminals.
PAGE 3
Bill of Materials www.ti.com 3 Bill of Materials Table 1. Bill of Materials Item Description Mfg., Part Number Package Value U1 Sync Switching Regulator Texas Instruments, LM34926 WSON-8 100V, 300mA T1 Coupled Inductor, 1500 VDC Coilcraft, LPD5030V-473ME 5mm x 5mm 47uH, 0.47A Alternate Part Wurth, 750312750 8.26mm x 6.60mm 22uH, 0.76A Schottky Diode Diodes Inc., DFLS1100-7 Pwr–DI123 100V, 1A D1 D2 Schottky Diode Diodes Inc.
PAGE 4
Performance Curves 4 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 750kHz, VOUT1=10V Figure 4. Steady State Waveform (VIN=48V, IOUT1=0mA, IOUT2= 100mA) Figure 5.
PAGE 5
PC Board Layout www.ti.com 5 PC Board Layout Figure 6.
PAGE 6
PC Board Layout www.ti.com Figure 7.
PAGE 7
PC Board Layout www.ti.com Figure 8.
PAGE 8
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.