LTC3603 Linear Dimensions Semiconductor, LTC3603 Datasheet - Page 15

• Manufacturer Part Number: LTC3603
• Description: Monolithic Synchronous Step-Down Regulator
• Manufacturer: Linear Dimensions Semiconductor

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APPLICATIONS INFORMATION
capacitance and a ceramic capacitor in parallel to lower
the total effective ESR. For this design, a 100μF ceramic
capacitor will be used. C
current rating of:
Decoupling the PV
adequate for most applications.
The output voltage can now be programmed by choosing
the values of R1 and R2. Choose R1 = 105k and calculate
R2 as:
Choose a standard value of R2 = 475k. The voltage on
the MODE pin will be set to 0.6V by tying the MODE pin
to the FB pin. This will set the burst current equal to ap-
proximately 1A. Figure 6 shows a complete schematic for
this design example.
I
R
RMS
2
=
R
=
1
2 5
⎛
⎜
⎝
.
V
0 6
A
OUT
.
•
V
3 3
12
L1: VISHAY IHLP2525CZER2R2MO1
C
C
.
IN
IN
OUT
–
105k
: TAIYO YUDEN TMK325BJ226MM-T
C
1nF
V
R1
V
1
PGOOD
ITH
: TDK C3225X5ROJ107M
pin with a 22μF ceramic capacitor is
⎞
⎟ =
⎠
•
IN
200k
475k
R
472 5
R2
should be sized for a maximum
PG
3 3
12
4.32k
R
105k
R
.
OSC
ITH
Figure 6. 12V to 3.3V, 2.5A Regulator at 1MHz, Burst Mode Operation
V
V
.
–
k
1 1 12
C
10pF
=
FB
.
A
RMS
SYNC/MODE
PGOOD
RT
ITH
V
RUN
TRACK/SS
PGND
FB
LTC3603
INTV
BOOST
PGND
PGND
PV
PV
SW
SW
SW
CC
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC3603. Check the following in your layout:
1. A ground plane is recommended. If a ground plane layer
2. Connect the (+) terminal of the input capacitor(s), C
3. Keep the switching node, SW, away from all sensitive
4. Flood all unused areas on all layers with copper. Flooding
IN
IN
is not used, the signal and power grounds should be
segregated with all small signal components returning
to the SGND pin at one point which is then connected
to the PGND pin close to the LTC3603.
close as possible to the PV
the AC current into the internal power MOSFETs.
small signal nodes.
with copper will reduce the temperature rise of power
components. You can connect the copper areas to any
DC net (PV
DC rail in your system).
IN
C
0.22μF
D1
, INTV
BST
2.2μH
C
1μF
VCC
L1
CC
, V
OUT
C
22μF
V
12V
IN
IN
IN
, PGND, SGND, or any other
pin. This capacitor provides
3603 F06
C
100μF
OUT
V
3.3V
2.5A
OUT
LTC3603
15
IN
3603f
, as