LTC3834 Datasheet, PDF (24/28 Pages) Linear Technology – 30μA IQ Synchronous Step-Down Controller

LTC3834
APPLICATIONS INFORMATION
high current output loading at lower input voltages, look
for inductive coupling between CIN, Schottky and the top
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.
C1
C_B
V_IN
1nF
C_IN
M1
L1
V_OUT
M2
D1
OPTIONAL
C_OUT
D_B
3834 F09
Figure 9. LTC3834 Recommended Printed Circuit Layout Diagram
V_IN
R_IN
C_IN
SW
L1
R_SENSE
V_OUT
D1
C_OUT
24
BOLD LINES INDICATE HIGH SWITCHING
CURRENT. KEEP LINES TO A MINIMUM LENGTH.
Figure 10. Branch Current Waveforms
R_L1
3834 F10
3834fb