Texas Instruments LM3404 Evaluation Boards LM3404FSTDIMEV/NOPB LM3404FSTDIMEV/NOPB ユーザーズマニュアル
製品コード
LM3404FSTDIMEV/NOPB
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
by the SW and BOOT pins and capacitor C
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
by the SW and BOOT pins and capacitor C
B
. To minimize this loop at the EMI it generates, keep C
B
close to the
SW and BOOT pins.
CURRENT SENSING
The CS pin is a high-impedance input, and the loop created by R
SNS
, R
Z
(if used), the CS pin and ground should
be made as small as possible to maximize noise rejection. R
SNS
should therefore be placed as close as possible
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.
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
31
Product Folder Links: