LM3404MREVAL National Semiconductor, LM3404MREVAL Datasheet

LM3404MREVAL

Manufacturer Part Number

LM3404MREVAL

Description

BOARD EVALUATION LM3404MR

Manufacturer

National Semiconductor

Series

PowerWise®r

Datasheets

1.LM3404MANOPB.pdf (28 pages)

2.LM3404MREVAL.pdf (6 pages)

Specifications of LM3404MREVAL

Current - Output / Channel

Outputs And Type

1, Non-Isolated

Voltage - Output

37V

Features

Dimmable

Voltage - Input

6 ~ 42 V

Utilized Ic / Part

LM3404

Lead Free Status / RoHS Status

Contains lead / RoHS non-compliant

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LM3402 and LM3404 High

Power PSOP-8 Evaluation

Board

Introduction

The LM3402/02HV and LM3404/04HV are buck regulator de-

rived controlled current sources designed to drive a series

string of high power, high brightness LEDs (HBLEDs) such as

the Luxeon™ K2 Emitter at forward currents of up to 0.5A

(LM3402/02HV) or 1.0A (LM3404/04HV). This evaluation

board demonstrates the enhanced thermal performance of

the PSOP-8 package option of any of those four ICs. The

LM3404HV was chosen for the example circuit because the

combination of high output current, high input voltage, and

high duty cycle create the greatest demand for low junction-

to-ambient

LM3404/04HV in SO-8 can also be used with this evaluation

board, with reduced thermal performance.

LED drivers are often placed in small, closed spaces with no

air flow and high ambient temperature due to the dissipation

Thermal Performance

The PSOP-8 package is pin-for-pin compatible with the SO-8

package with the exception of the thermal pad, or exposed

die attach paddle (DAP). The DAP is electrically connected to

system ground. When the DAP is properly soldered to an area

of copper on the top layer, bottom layer, internal planes, or

combinations of various layers, the θ

can be significantly lower than that of the SO-8 package or

MSOP-8 package in the case of the LM3402/02HV. The

PSOP-8 evaluation board is two layers of 1oz copper each,

and measures 1.25" by 1.95". The DAP is soldered to ap-

proximately one square inch of top and two square inches of

bottom layer copper. Five thermal vias connect the DAP to

the bottom layer of the PCB, and the recommended DAP/via

layout is shown in Figure 2.

thermal

resistance

(θ

of the LM3404/04HV

300092

Note

FIGURE 1. Standard Schematic

that

the

National Semiconductor

Application Note 1585

Chris Richardson

October 2007

of the LEDs. When properly soldered the PSOP-8 package

offers a θ

SO-8 package, and as little as one-third that of the MSOP-8

package.

Circuit Performance with LM3404HV

This evaluation board uses the LM3404HV to provide a con-

stant forward current of 1.0A ±10% to a string of ten series-

connected HBLEDs with a forward voltage of approximately

3.7V each from an input of 48V ±5%. The LED ripple current,

Δi

550 kHz ± 10%. The circuit can operate over an extended

input voltage range of 40V to 60V, however output current

may exceed the ±10% specification.

, will not exceed 80 mA

FIGURE 2. Thermal Pad and Via Layout

that is as little as one-half that of the standard

P-P

, and the switching frequency is

30009221

www.national.com

30009220

Related parts for LM3404MREVAL

LM3404MREVAL Summary of contents

Page 1

... Five thermal vias connect the DAP to the bottom layer of the PCB, and the recommended DAP/via layout is shown in Figure 2. © 2007 National Semiconductor Corporation National Semiconductor Application Note 1585 Chris Richardson October 2007 of the LEDs ...

Page 2

Calibrated testing was performed on the PSOP-8 evaluation board to compare the performance of the PSOP-8 with the DAP soldered and the standard SO-8 package. The example circuit dissipation is approximately LM3404/04HV datasheet for detailed thermal calculations.) For dissipation ranging ...

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LM3404MREVAL National Semiconductor, LM3404MREVAL Datasheet

LM3404MREVAL

Specifications of LM3404MREVAL

Related parts for LM3404MREVAL

LM3404MREVAL Summary of contents

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