LT3479 LINER [Linear Technology], LT3479 Datasheet - Page 10

• Manufacturer Part Number: LT3479
• Description: 3A, Full Featured DC/DC Converter with Soft-Start and Inrush Current Protection
• Manufacturer: LINER [Linear Technology]

LT3479
APPLICATIONS INFORMATION
10
Figure 5. Start-Up with No Soft-Start Capacitor
2A/DIV
5V/DIV
2A/DIV
5V/DIV
V
V
OUT
OUT
I
I
L
L
Figure 6. Start-Up with C
TO GND
TO V
TO V
MINIMIZE THE AREA
IN
S
OF THIS TRACE
0.2MS/DIV
0.2ms/DIV
C
S
SS
L1
= 22nF
C
3479 F05
3479 F06
IN
Figure 4. Suggested Board Layout
R
T
SW
SW
L
V
V
R
SHDN
S
IN
T
TO SHDN
Switching Frequency
The switching frequency of the LT3479 is set by an exter-
nal resistor attached to the R
open. A resistor must always be connected for proper
operation. See Table 4 and Figure 7 for resistor values
and corresponding frequencies.
Table 4. Switching Frequency
SWITCHING FREQUENCY (MHz)
D
LT3479
3.5
2.5
1.5
0.5
0.2
3
2
1
GND
GND
V
C
FBN
FBP
REF
PLACE VIAS AROUND EXPOSED PAD
TO ENHANCE THERMAL PERFORMANCE
OUT
SS
V
C
C
R2
SS
R1
C
T
C
3479 F04
pin. Do not leave this pin
R
TO V
C
OUT
R
T
1.78
2.87
4.32
6.49
10.2
17.8
39.2
113
(kΩ)
3479fb