LT1932 Linear Technology, LT1932 Datasheet - Page 9

• Manufacturer Part Number: LT1932
• Description: Constant-Current/ Constant-Voltage 1.4MHz Step-Up DC/DC Converter
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
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
pin and not be shared with any other component, ensuring
a clean, noise-free connection. Recommended compo-
nent placement is shown in Figure 7.
TYPICAL APPLICATIO S
V
5V
IN
C1: TAIYO YUDEN JMK212BJ475
C2: TAIYO YUDEN GMK325BJ225
D1: ZETEX ZHCS400
L1: MURATA LQH3C100M24
DIMMING
CONTROL
C1
4.7 F
5V DC
SET
51.1k
resistor should be tied directly to the GND
5V Driver for 16 White LEDs
5
SHDN
U
R
V
SET
IN
6
4
R
750
LT1932
10 H
SET
L1
U
GND
SW
LED
1
2
[phone]
[phone]
[phone]
[phone]
D1
3
U
30mA
W
100
100
U
1932 TA14a
C2
2.2 F
Figure 7. Recommended Component Placement
80
75
70
65
60
55
50
0
GND
C2
D1
5
LED CURRENT (mA)
10
1
2
3
L1
Efficiency
15
R
C1
SET
6
5
4
20
25
1932 TA14b
1932 F07
30
LT1932
V
SHDN
DIMMING
CONTROL
IN
9