Datasheet

9
LT1932
APPLICATIO S I FOR ATIO
WUUU
TYPICAL APPLICATIO S
U
Figure 7. Recommended Component Placement
C1
L1
D1
GND
C2
R
SET
1932 F07
1
2
3
6
5
4
DIMMING
CONTROL
SHDN
V
IN
Board Layout Considerations
As with all switching regulators, careful attention must be
paid to the PCB board layout and component placement.
To maximize efficiency, switch rise and fall times are made
as short as possible. To prevent radiation and high fre-
quency resonance problems, proper layout of the high
frequency switching path is essential. Minimize the length
and area of all traces connected to the SW pin and always
use a ground plane under the switching regulator to
minimize interplane coupling. The signal path including
the switch, output diode D1 and output capacitor C2,
contains nanosecond rise and fall times and should be
kept as short as possible. In addition, the ground connec-
tion for the R
SET
resistor should be tied directly to the GND
pin and not be shared with any other component, ensuring
a clean, noise-free connection. Recommended compo-
nent placement is shown in Figure 7.
5V Driver for 16 White LEDs
V
IN
SW
D1
30mA
1932 TA14a
L1
10µH
V
IN
5V
LT1932
SHDN
C1: TAIYO YUDEN JMK212BJ475 [phone]
C2: TAIYO YUDEN GMK325BJ225 [phone]
D1: ZETEX ZHCS400 [phone]
L1: MURATA LQH3C100M24 [phone]
61
4
R
SET
750Ω
5V DC
DIMMING
CONTROL
C1
4.7µF
C2
2.2µF
51.1k
2
3
100Ω
5
LED
R
SET
GND
100Ω
Efficiency
LED CURRENT (mA)
0
50
EFFICIENCY (%)
55
60
65
70
75
80
10 20 3051525
1932 TA14b