LTC3826 Linear Technology, LTC3826 Datasheet - Page 27

• Manufacturer Part Number: LTC3826
• Description: 2-Phase Synchronous Step-Down Controller
• Manufacturer: Linear Technology

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APPLICATIONS INFORMATION
C
temperature assuming only this channel is on. C
chosen with an ESR of 0.02Ω for low output ripple. The
output ripple in continuous mode will be highest at the
maximum input voltage. The output voltage ripple due to
ESR is approximately:
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of
IN
V
is chosen for an RMS current rating of at least 3A at
ORIPPLE
= R
ESR
(ΔI
L
) = 0.02Ω(1.67A) = 33mV
f
IN
I
V
SENSE1
SENSE1
PLLLPF
PHASMD
CLKOUT
PLLIN/MODE
RUN1
RUN2
SGND
SENSE2
SENSE2
V
I
TRACK/SS2
TH1
TH2
FB1
FB2
Figure 11. Recommended Printed Circuit Layout Diagram
+
–
–
+
LTC3826
TRACK/SS1
PGOOD2
PGOOD1
BOOST1
BOOST2
EXTV
FOLDIS
INTV
PGND
SW1
SW2
BG1
BG2
TG1
TG2
V
CC
CC
IN
P-P
OUT
is
R
PGOOD2
PU2
the IC. These items are also illustrated graphically in the
layout diagram of Figure 11. Figure 12 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:
1. Are the top N-channel MOSFETs M1 and M3 located
within 1cm of each other with a common drain connec-
tion at C
for the two channels as it can cause a large resonant
loop.
C
C
V
(<8.5V)
C
B1
B2
PULL-UP
INTVCC
C
VIN
R
PGOOD1
IN
PU1
? Do not attempt to split the input decoupling
CERAMIC
V
R
M1
V
(<8.5V)
M3
IN
IN
PULL-UP
1μF
CERAMIC
M2
M4
1μF
L1
C
L2
IN
R
R
SENSE
SENSE
C
C
D1
OUT1
OUT2
D2
3826 F11
LTC3826
V
GND
V
OUT1
OUT2
27
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