LM5035CEVAL/NOPB National Semiconductor, LM5035CEVAL/NOPB Datasheet

LM5035CEVAL/NOPB

Manufacturer Part Number

LM5035CEVAL/NOPB

Description

EVAL BOARD FOR LM5035C

Manufacturer

National Semiconductor

Datasheet

1.LM5035CEVALNOPB.pdf (14 pages)

Specifications of LM5035CEVAL/NOPB

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

Current page: 1 of 14
Download datasheet (335Kb)

LM5035C Evaluation Board

Introduction

The LM5035C evaluation board is designed to provide the

design engineer with a fully functional power converter based

on the Half Bridge topology to evaluate the LM5035C con-

troller. The LM5035C is a functional variant of the LM5035B

Half-Bridge PWM Controller. The amplitude of the SR control

signals are 5V instead of the V

is provided in an industry standard quarter-brick footprint.

The performance of the evaluation board is as follows:

•

The printed circuit board consists of 6 layers; 2 ounce copper

outer layers and 3 ounce copper inner layers on FR4 material

with a total thickness of 0.062 inches. The unit is designed for

continuous operation at rated load at <40°C and a minimum

airflow of 200 CFM.

Theory of Operation

Power converters based on the Half Bridge topology offer

high efficiency and good power handling capability in appli-

cations up to 500 Watts. The operation of the transformer

causes the flux to swing in both directions, thereby better uti-

lizing the magnetic core.

The Half Bridge converter is derived from the Buck topology

family, employing separate high voltage (HO) and low voltage

Input operating range: 36V to 75V

Output voltage: 3.3V

Output current: 0 to 30A

Measured efficiency: 89% at 30A, 92% at 15A

Frequency of operation: 400kHz

Board size: 2.28 x 1.45 x 0.5 inches

Load Regulation: 0.2%

Line Regulation: 0.1%

Line UVLO (33.9V/31.9V on/off)

Line OVP (79.4V/78.3V off/on)

Hiccup current limit

level. The evaluation board

301195

National Semiconductor

Application Note 2043

Ajay Hari

March 18, 2010

(LO) modulating power switches with independent pulse

width timing. The main difference between the topologies are,

the Half Bridge topology employs a transformer to provide in-

put / output ground isolation and a step down or step up

function.

Each cycle, the main primary switch turns on and applies one-

half the input voltage across the primary winding, which has

8 turns. The transformer secondary has 2 turns, leading to a

4:1 step-down of the input voltage. For an output voltage of

3.3V the composite duty cycle (D) of the primary switches

varies from approximately 75% (low line) to 35% (high line).

The secondary employs synchronous rectification controlled

by the LM5035C. During soft-start, the sync FET body diodes

act as the secondary rectifiers until the main transformer en-

ergizes the gate drivers. The DLY resistor programs the non-

overlap timing for the sync FETs to maximize efficiency while

eliminating shoot through current. The Sync FET control sig-

nals are sent across the isolation boundary using a digital

isolator.

Feedback from the output is processed by an amplifier and

reference, generating an error voltage, which is coupled back

to the primary side control through an optocoupler. The

COMP input to the LM5035C greatly increases the achievable

loop bandwidth. The capacitance effect (and associated pole)

of the optocoupler is reduced by holding the voltage across

the optocoupler constant. The LM5035C voltage mode con-

troller pulse width modulates the error signal with a ramp

signal derived from the line voltage (feedforwarding) to re-

duce the response time to input voltage changes. A standard

“type III” network is used for the compensator.

The evaluation board can be synchronized to an external

clock with a recommended frequency range of 420KHz to

500KHz.

www.national.com

Related parts for LM5035CEVAL/NOPB

LM5035CEVAL/NOPB Summary of contents

Page 1

... The Half Bridge converter is derived from the Buck topology family, employing separate high voltage (HO) and low voltage © 2010 National Semiconductor Corporation National Semiconductor Application Note 2043 Ajay Hari ...

Page 2

Powering and Loading Considerations When applying power to the LM5035C evaluation board cer- tain precautions need to be followed. A misconnection can damage the assembly. Proper Connections When operated at low input voltages the evaluation board can draw up to ...

Page 3

A quick efficiency check is the best way to confirm that ev- erything is operating properly. If something is amiss you can be reasonably sure that it will affect the efficiency adversely. Few parameters can be incorrect in a switching ...

Page 4

Performance Characteristics TURN-ON WAVEFORMS When applying power to the LM5035C evaluation board a certain sequence of events occurs. Soft-start capacitor values and other components allow for a minimal output voltage for a short time until the feedback loop can stabilize ...

Page 5

Conditions: Input Voltage = 72VDC Output Current = 5A Trace 1: Q2 drain voltage Volts/div = 10V Horizontal Resolution = 1µs/div FIGURE 5. 30119508 Conditions: Input Voltage = 48VDC Output Current = 5A Upper Trace: SR1, Q4 gate Volts/div = ...

Page 6

Application Circuit www.national.com 6 ...

Page 7

Item Part Description 1 LM5035C Controller MH20 2 LM5110-1M Dual Driver 3 LM8261M5 Op Amp SOT23-5 4 LM4041AIM3-1.2 Ref Amp SOT23 5 Opto-Coupler PS2811-1M 6 Digital Isolator IC SOIC-8 7 Cer Cap 47pF 50V COG 0603 8 Cer Cap 150pF ...

Page 8

Item Part Description 38 Res 15K Ohm 0.1W 1% 0603 39 Res 20K Ohm 0.1W 1% 0603 40 Res 25.5K Ohm 0.1W 1% 0603 41 Res 100K Ohm 0.1W 1% 0603 42 NU 0805 43 Res 10 OHM 1/10W 1% ...

Page 9

PCB Layouts Top Side Bottom Side 9 30119510 30119511 www.national.com ...

Page 10

Layer 1 Layer 2 10 30119512 30119513 ...

Page 11

Layer 3 Layer 4 11 30119514 30119515 www.national.com ...

Page 12

Layer 5 Layer 6 12 30119516 30119517 ...

Page 13

Notes 13 www.national.com ...

Page 14

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock and Timing www.national.com/timing Data Converters www.national.com/adc Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www ...

Related keywords

LM5035CEVAL/NOPB datasheet
LM5035CEVAL/NOPB data sheet
LM5035CEVAL/NOPB pdf datasheet
LM5035CEVAL/NOPB component
LM5035CEVAL/NOPB part
LM5035CEVAL/NOPB distributor
LM5035CEVAL/NOPB RoHS
LM5035CEVAL/NOPB datasheet download