LM3404, LM3404HV

www.ti.com

SNVS465F – OCTOBER 2006 – REVISED MAY 2013

any other circuit path. The continuous current paths on the ground net can be routed on the system ground plane

with less risk of injecting noise into other circuits. The path between the input source and the input capacitor and

the path between the recirculating diode and the LEDs/current sense resistor are examples of continuous current

paths. In contrast, the path between the recirculating diode and the input capacitor carries a large pulsating

current. This path should be routed with a short, thick shape, preferably on the component side of the PCB.

Multiple vias in parallel should be used right at the pad of the input capacitor to connect the component side

shapes to the ground plane. A second pulsating current loop that is often ignored is the gate drive loop formed

SW and BOOT pins.

CURRENT SENSING

to the CS and GND pins of the IC.

REMOTE LED ARRAYS

In some applications the LED or LED array can be far away (several inches or more) from the LM3404/04HV, or

on a separate PCB connected by a wiring harness. When an output capacitor is used and the LED array is large

or separated from the rest of the converter, the output capacitor should be placed close to the LEDs to reduce

the effects of parasitic inductance on the AC impedance of the capacitor. The current sense resistor should

remain on the same PCB, close to the LM3404/04HV.

Table 1. BOM for Design Example 1

ID

Part Number

Type

Size

Parameters

Qty

Vendor

U1

LM3404

LED Driver

SOIC-8

42V, 1.2A

1

TI

L1

SLF10145T-470M1R4

Inductor

10 x 10 x 4.5mm

47 µH, 1.4A, 120 m

Ω

1

TDK

D1

CMSH2-40

Schottky Diode

SMB

40V, 2A

1

Central Semi

Cf

VJ0805Y104KXXAT

Capacitor

0805

100 nF 10%

1

Vishay

Cb

VJ0805Y103KXXAT

Capacitor

0805

10 nF 10%

1

Vishay

Cin

C3225X7R1H335M

Capacitor

1210

3.3 µF, 50V

1

TDK

Co

C2012X7R1E105M

Capacitor

0805

1.0 µF, 25V

1

TDK

Rsns

ERJ8BQFR33V

Resistor

1206

0.33

Ω 1%

1

Panasonic

Ron

CRCW08051333F

Resistor

0805

133 k

Ω 1%

1

Vishay

Table 2. BOM for Design Example 2

ID

Part Number

Type

Size

Parameters

Qty

Vendor

U1

LM3404HV

LED Driver

SOIC-8

75V, 1.2A

1

TI

L1

DO5022P-334

Inductor

18.5 x 15.4 x 7.1mm

330 µH, 1.9A, 0.56

Ω

1

Coilcraft

D1

CMSH1-60M

Schottky Diode

SMA

60V, 1A

1

Central Semi

Cf

VJ0805Y104KXXAT

Capacitor

0805

100 nF 10%

1

Vishay

Cb

VJ0805Y103KXXAT

Capacitor

0805

10 nF 10%

1

Vishay

Cin

C4532X7R2A225M

Capacitor

1812

2.2 µF, 100V

1

TDK

Co

C3216X7R2A154M

Capacitor

1206

0.15 µF, 100V

1

TDK

Rsns

ERJ6BQFR43V

Resistor

0805

0.43

Ω 1%

1

Panasonic

Ron

CRCW08051184F

Resistor

0805

1.18 M

Ω 1%

1

Vishay

Copyright © 2006–2013, Texas Instruments Incorporated

Submit Documentation Feedback

31

Product Folder Links: LM3404 LM3404HV