LTC3786EUD#PBF Linear Technology, LTC3786EUD#PBF Datasheet - Page 23

• Manufacturer Part Number: LTC3786EUD#PBF
• Description: IC, DC-DC CONV, 550kHz, QFN16
• Manufacturer: Linear Technology

Specifications of LTC3786EUD#PBF

• Primary Input Voltage: 38V
• No. Of Outputs: 1
• Output Voltage: 60V
• No. Of Pins: 16
• Operating Temperature Range: -40°C To +125°C
• Peak Reflow Compatible (260 C): Yes
• Switching Frequency Max: 550kHz
• Msl: MSL 1 - Unlimited
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
Reduce V
high duty cycle. Check the operation of the undervoltage
lockout circuit by further lowering V
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,
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
IN
from its nominal level to verify operation with
V
IN
R
IN
BOLD LINES INDICATE HIGH SWITCHING CURRENT.
KEEP LINES TO A MINIMUM LENGTH
C
IN
f
IN
Figure 6. Recommended Printed Circuit Layout Diagram
R
IN
SENSE
SENSE
SENSE
FREQ
PLLIN/MODE
RUN
VFB
ITH
SS
while monitoring
LTC3786
+
–
Figure 7. Branch Current Waveforms
L1
PGOOD
BOOST
INTV
VBIAS
GND
SW
BG
TG
CC
SW
V
PULLUP
C
effects of differential noise injection due to high frequency
capacitive coupling.
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 hook-up 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.
B
M2
M1
L1
C
GND
OUT
V
R
OUT
SENSE
+
+
3786 F06
V
IN
3786 F07
V
OUT
R
L
LTC3786
23
3786f