Datasheet

LT3759
24
3759fc
For more information www.linear.com/3759
• In flyback configuration, the high di/dt primary loop
contains the input capacitor, the primary winding, the
power MOSFET and sensing resistor. The high di/dt
secondary loop contains the output capacitor, the sec-
ondary winding and the output diode.
• In SEPIC configuration, the high di/dt loop contains
the power MOSFET, sense resistor, output capacitor,
Schottky diode and the coupling capacitor.
• In inverting configuration, the high di/dt loop contains
power MOSFET, sense resistor, Schottky diode and the
coupling capacitor.
Check the stress on the power MOSFET by measuring its
drain-to-source voltage directly across the device terminals
(reference the ground of a single scope probe directly to
the source pad on the PC board). Beware of inductive
ringing, which can exceed the maximum specified voltage
rating of the MOSFET. If this ringing cannot be avoided,
and exceeds the maximum rating of the device, either
choose a higher voltage device or specify an avalancher-
ated power MOSFET.
The small-signal components should be placed away from
high frequency switching nodes. For optimum load regula-
tion and true remote sensing, the top of the output voltage
sensing resistor divider should connect independently to
the top of the output capacitor (Kelvin connection), staying
away from any high dV/dt traces. Place the divider resis-
tors near the LT3759 in order to keep the high impedance
FBX node short.
Figure 10 shows the suggested layout of 1.8V to 3.3V
input, 5V/2A Output Boost Converter.
APPLICATIONS INFORMATION
Figure 10. The Suggested Boost Converter Layout
3759 F10
V
OUT
L1
VIAS TO GROUND
PLANE
D1
C
OUT1
C
OUT2
C
IN
1
2
8
7
3
4
6
5
M1
R
C
R1
R2
C
SS
R
T
R3
R4
C
VCC
C
DRIVE
C
C1
C
C2
LT3759
13
2
3
1
4
5
6
10
11
12
7
8
9
R
S
R
PGOOD
V
IN
V
IN
VIAS TO V
IN
GND
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