lt3467aes67 Linear Technology Corporation, lt3467aes67 Datasheet - Page 9

• Manufacturer Part Number: lt3467aes67
• Description: 1.1a Step-up Dc/dc Converter With Integrated Soft-start
• Manufacturer: Linear Technology Corporation

APPLICATIONS
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.
R
LOAD CURRENT
LOAD CURRENT
1
AC COUPLED
AC COUPLED
AC COUPLED
AC COUPLED
AC COUPLED
AC COUPLED
=
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 22pF Phase Lead Capacitor
100mA/DIV
200mV/DIV
100mA/DIV
200mV/DIV
R
5A/DIV
2
5A/DIV
V
⎛
⎝ ⎜
V
OUT
OUT
I
1 255
I
L1
L1
V
.
OUT
V
U
–
1
⎞
⎠ ⎟
INFORMATION
U
20μs/DIV
20μs/DIV
W
3467 F03
U
3467 F04
LAYOUT HINTS
The high speed operation of the LT3467/LT3467A de-
mands careful attention to board layout. You will not get
advertised 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
VIA’s under the exposed PAD. These should connect to a
local ground plane for better thermal performance.
V
OUT
V
OUT
C2
C2
Suggested Layout—ThinSOT
GND
Suggested Layout—DFN
GND
D1
D1
L1
FB
FB
Figure 5A.
Figure 5B.
1
2
3
1
2
3
4
L1
C3
LT3467/LT3467A
C3
R1
R2
8
7
6
5
R2
R1
C1
V
6
5
4
OUT
V
C1
OUT
SS
C
3467 F05B
SS
3467 F05A
C
SS
SHDN
V
SHDN
V
IN
IN
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