Datasheet

LT3497
14
3497f
Li-Ion to 1/2 White LEDs
Conversion Effi ciency
BOARD LAYOUT CONSIDERATIONS
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To prevent electromagnetic interference (EMI) problems,
proper layout of high frequency switching paths is essential.
Minimize the length and area of all traces connected to
the switching node pins (SW1 and SW2). Keep the sense
voltage pins (CAP1, CAP2, LED1 and LED2) away from
APPLICATIONS INFORMATION
5
4
1
2
3
7
6
8
9
10
CAP2
SW2
SW1
CAP1
VIAS TO
GROUND PLANE
VIA TO
GROUND PLANE
VIA TO
GROUND
PLANE
L1
L2
LED2
LED1
3497 F12
C
OUT2
C
OUT1
GND
CTRL2
CTRL1
C
IN
V
IN
the switching node. Place the output capacitors (C
OUT1
and C
OUT2
) next to the output pins (CAP1 and CAP2).
The placement of a bypass capacitor on V
IN
needs to be
in close proximity to the IC to fi lter EMI noise from SW1
and SW2. Always use a ground plane under the switching
regulator to minimize interplane coupling. Recommended
component placement is shown in Figure 12.
Figure 12. Recommended Component Placement
SW1 V
IN
LT3497
GND
SW2
L2
10µH
R
SENSE2
10Ω
R
SENSE1
10Ω
C3
1µF
C1
1µF
C2
1µF
3497 TA02a
V
IN
3V TO 5V
L1
10µH
CAP1 CAP2
LED1 LED2
CTRL1
SHUTDOWN
AND DIMMING
CONTROL 1
SHUTDOWN
AND DIMMING
CONTROL 2
CTRL2
OFF ON
OFF ON
C1, C2: TAIYO YUDEN GMK212BJ105KG
C3: TAIYO YUDEN LMK212BJ105MG
L1, L2: MURATA LQH32CN100K53
LED CURRENT (mA)
0
EFFICIENCY (%)
50
55
60
20
3497 TA02b
45
40
30
5
10
15
35
70
65
V
IN
= 3.6V
1/2LEDs
TYPICAL APPLICATIONS