LTC3631 Linear Technology Corporation, LTC3631 Datasheet - Page 16

• Manufacturer Part Number: LTC3631
• Description: High Voltage 100mA Synchronous Step-Down Converter
• Manufacturer: Linear Technology Corporation

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APPLICATIONS INFORMATION
LTC3631
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
the LTC3631. Check the following in your layout:
1. Large switched currents fl ow in the power switches
2. Connect the (+) terminal of the input capacitor, C
TYPICAL APPLICATIONS
16
4.5V TO 24V
and input capacitor. The loop formed by these compo-
nents should be as small as possible. A ground plane
is recommended to minimize ground impedance.
close as possible to the V
the AC current into the internal power MOSFETs.
3.3V, 100mA Regulator with Peak Current Soft-Start, Small Size
V
IN
22nF
C
SS
C
1μF
IN
C
C
L1: MURATA LQH43CN220K03
IN
OUT
: TDK C3216X7R1E105KT
: AVX 08056D106KAT2A
V
RUN
I
SS
SET
IN
LTC3631
GND
HYST
IN
SW
V
FB
pin. This capacitor provides
5V TO 45V
22μH
L1
V
IN
R1
294k
R2
93.1k
3642 TA03a
Figure 10. High Effi ciency 5V Regulator
C
4.7μF
IN
C
C
L1: TDK SLF7045T-101MR50-PF
IN
OUT
: TDK C5750X7R2A475MT
: AVX 1812D107MAT
C
10μF
OUT
V
RUN
HYST
I
SET
IN
IN
LTC3631
, as
GND
V
3.3V
100mA
OUT
V
SW
SS
FB
3. Keep the switching node, SW, away from all sensitive
4. Flood all unused area on all layers with copper. Flooding
100μH
L1
small signal nodes. The rapid transitions on the switching
node can couple to high impedance nodes, in particular
V
with copper will reduce the temperature rise of power
components. You can connect the copper areas to any
DC net (V
system).
3631 F10a
FB
C
47nF
SS
, and create increased output ripple.
R1
1.47M
R2
280k
INDUCTOR
IN
50mA/DIV
CURRENT
VOLTAGE
OUTPUT
, V
1V/DIV
OUT
C
100μF
OUT
, GND or any other DC rail in your
V
5V
OUT
Soft-Start Waveforms
500μs/DIV
3631 TA03b
3631fa