LTC3858 Linear Technology, LTC3858 Datasheet - Page 28

• Manufacturer Part Number: LTC3858
• Description: Synchronous Step-Down Controller
• Manufacturer: Linear Technology

Reduce V
of the regulator in dropout. Check the operation of the
undervoltage lockout circuit by further lowering V
monitoring the outputs to verify operation.
Investigate whether any problems exist only at higher out-
put currents or only at higher input voltages. If problems
coincide with high input voltages and low output currents,
look for capacitive coupling between the BOOST, SW, TG,
LTC3858
applicaTions inForMaTion

IN
from its nominal level to verify operation
f
IN
PHASMD
CLKOUT
PLLIN/MODE
RUN1
RUN2
SGND
I
V
SENSE1
SENSE1
FREQ
SENSE2
SENSE2
V
I
SS2
TH1
TH2
FB1
FB2
Figure 10. Recommended Printed Circuit Layout Diagram
LTC3858
+
–
–
+
PGOOD2
PGOOD1
BOOST1
BOOST2
EXTV
INTV
PGND
SW1
SW2
BG1
BG2
SS1
TG1
TG2
V
CC
CC
IN
IN
V
OUT1
while
R
and possibly BG connections and the sensitive voltage
and current pins. The capacitor placed across the current
sensing pins needs to be placed immediately adjacent to
the pins of the IC. This capacitor helps to minimize the
effects of differential noise injection due to high frequency
capacitive coupling. If problems are encountered with
high current output loading at lower input voltages, look
for inductive coupling between C
PGOOD2
PU2
C
C
V
(<6V)
C
B1
B2
PULL-UP
INTVCC
C
VIN
R
PGOOD1
PU1
CERAMIC
V
R
M1
V
(<6V)
M3
IN
IN
PULL-UP
1µF
CERAMIC
M2
M4
1µF
L1
C
L2
IN
IN
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R
R
SENSE
, Schottky and the top
SENSE
C
C
OUT1
OUT2
D1
D2
3858 F10
V
GND
V
OUT1
OUT2
3858fa