ltc1876eg-trpbf Linear Technology Corporation, ltc1876eg-trpbf Datasheet - Page 30

• Manufacturer Part Number: ltc1876eg-trpbf
• Description: High Efficiency, 2-phase, Dual Synchronous Step-down Switching Controller And Step-up Regulator
• Manufacturer: Linear Technology Corporation

LTC1876
APPLICATIO S I FOR ATIO
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC1876. These items are also illustrated graphically in
the layout diagram of Figure 15. The Figure 16 illustrates
the current waveforms present in the various branches of
the 2-phase synchronous regulators operating in the
continuous mode. Check the following in your layout:
30
V
OUT3
R3
C
R1
OUT3
U
INTV
R2
R4
R7
R8
D3
CC
U
3.3V
Figure 15. LTC1876 Recommended Printed Circuit Layout Diagram
10
11
12
13
14
15
16
17
18
1
2
3
4
5
6
7
8
9
RUN/SS1
SENSE1
SENSE1
V
FREQSET
STBYMD
FCB
I
SGND
3.3V
I
V
SENSE2
SENSE2
AUXSGND
AUXV
AUXSW
AUXSW
TH1
TH2
W
OSENSE1
OSENSE2
OUT
FB
LTC1876
+
–
–
+
L3
AUXPGND
AUXPGND
RUN/SS2
BOOST1
BOOST2
EXTV
AUXV
PGOOD
INTV
AUXSD
PGND
U
SW1
SW2
TG1
BG1
BG2
TG2
V
CC
CC
IN
IN
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
SHUTDOWN
1. Are the top N-channel MOSFETs M1 and M3 located
within 1cm of each other with a common drain connection
at C
two channels as it can cause a large resonant loop.
2. Is the ground of the step-down controller kept separate
from the ground of the step-up regulator? The regulator
ground should join the controller ground at the combined
C
signal and power grounds kept separate? The controller
OUT
C
C
C
C
AUXIN
B1
B2
IN
INTVCC
? Do not attempt to split the input decoupling for the
(–) plates. Within the controller circuitry, are the
V
(<7V)
PULL-UP
C
VIN
V
R
IN
IN
M3
M1
L1
C
L2
IN
3
3
1
1
M2
M4
R
R
SENSE
SENSE
C
C
OUT1
OUT2
D2
D1
2
2
4
4
1876 F15
V
OUT1
V
OUT2
1876fa