LT3467 LINER [Linear Technology], LT3467 Datasheet - Page 9

• Manufacturer Part Number: LT3467
• Description: 1.1A Step-Up DC/DC Converter with Integrated Soft-Start
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Setting Output Voltage
To set the output voltage, select the values of R1 and R2
(see Figure 2) according to the following equation.
A good value for R2 is 13.3k which sets the current in the
resistor divider chain to 1.255V/13.3k = 94μA.
LOAD CURRENT
LOAD CURRENT
AC COUPLED
AC COUPLED
AC COUPLED
AC COUPLED
AC COUPLED
AC COUPLED
R
100mA/DIV
100mA/DIV
200mV/DIV
200mV/DIV
1
=
Figure 3. Transient Response of Figure 8’s Step-Up
Converter without Phase Lead Capacitor
Figure 4. Transient Response of Figure 8’s Step-Up
Converter with a 22pF Phase Lead Capacitor
5A/DIV
5A/DIV
V
V
R
OUT
OUT
I
I
L1
L1
2
⎛
⎝ ⎜
1 255
V
.
OUT
V
–
1
⎞
⎠ ⎟
20μs/DIV
20μs/DIV
3467 F03
3467 F04
Layout Hints
The high speed operation of the LT3467/LT3467A demands
careful attention to board layout. You will not get adver-
tised performance with careless layout. Figure 5a shows
the recommended component placement for the ThinSOT
package. Figure 5b shows the recommended component
placement for the DFN package. Note the vias under the
Exposed Pad. These should connect to a local ground
plane for better thermal performance.
V
OUT
V
Figure 5a. Suggested Layout—ThinSOT
OUT
Figure 5b. Suggested Layout—DFN
C2
C2
GND
GND
D1
D1
L1
FB
FB
LT3467/LT3467A
1
2
3
1
2
3
4
L1
C3
C3
R1
R2
8
7
6
5
R2
R1
C1
V
6
5
4
OUT
V
C1
OUT
SS
C
SS
3467 F05b
3467 F05a
C
SS
SHDN
V
V
IN
SHDN
IN
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