Datasheet

LTC3835
24
3835fd
APPLICATIONS INFORMATION
MOSFET components to the sensitive current and voltage
sensing traces. In addition, investigate common ground
path voltage pickup between these components and the
SGND pin of the IC.
An embarrassing problem, which can be missed in an
otherwise properly working switching regulator, results
when the current sensing leads are hooked up backwards.
The output voltage under this improper hookup will still
be maintained but the advantages of current mode control
will not be realized. Compensation of the voltage loop will
be much more sensitive to component selection. This
behavior can be investigated by temporarily shorting out
the current sensing resistor—don’t worry, the regulator
will still maintain control of the output voltage.
Figure 9. LTC3835 Recommended Printed Circuit Layout Diagram
C1
1nF
C
B
D
B
M2
M1
C
IN
L1
C
OUT
V
OUT
V
IN
3835 F09
CLKOUT PLLLPF I
TH
TRACK/SS V
FB
SGND PGND BG INTV
CC
EXTV
CC
PHASMD
PLLIN/MODE
PGOOD
SENSE
+
SENSE
–
RUN
BOOST
TG
SW
V
IN
LTC3835EFE
D1
OPTIONAL
Figure 10. Branch Current Waveforms
R
L1
D1
L1
SW
R
SENSE
V
OUT
C
OUT
V
IN
C
IN
R
IN
BOLD LINES INDICATE HIGH SWITCHING
CURRENT. KEEP LINES TO A MINIMUM LENGTH.
3835 F10