LTC3609EWKG#PBF Linear Technology, LTC3609EWKG#PBF Datasheet - Page 19

• Manufacturer Part Number: LTC3609EWKG#PBF
• Description: IC DC/DC CONV STP-DWN 6A 52-QFN
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC3609EWKG#PBF

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.6 ~ 36 V
• Current - Output: 6A
• Voltage - Input: 4 ~ 32 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 52-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Frequency - Switching: -

applicaTions inForMaTion
How to Reduce SW Ringing
As with any switching regulator, there will be voltage ring-
ing on the SW node, especially for high input voltages.
The ringing amplitude and duration is dependent on the
switching speed (gate drive), layout (parasitic inductance)
and MOSFET output capacitance. This ringing contributes
to the overall EMI, noise and high frequency ripple. One
way to reduce ringing is to optimize layout. A good layout
minimizes parasitic inductance. Adding RC snubbers from
SW to GND is also an effective way to reduce ringing. Finally,
adding a resistor in series with the BOOST pin will slow
down the MOSFET turn-on slew rate to dampen ringing,
but at the cost of reduced efficiency. Note that since the
IC is buffered from the high frequency transients by PCB
and bondwire inductances, the ringing by itself is normally
not a concern for controller reliability.
PC Board Layout Checklist
When laying out a PC board follow one of the two sug-
gested approaches. The simple PC board layout requires
a dedicated ground plane layer. Also, for higher currents, a
multilayer board is recommended to help with heat sinking
of power components.
• The ground plane layer should not have any traces and
• Place C
• Keep small-signal components close to the LTC3609.
• Ground connections (including LTC3609 SGND and
it should be as close as possible to the layer with the
LTC3609.
the LTC3609. It may help to have some components
on the bottom side of the board.
PGND) should be made through immediate vias to
the ground plane. Use several larger vias for power
components.
IN
and C
OUT
all in one compact area, close to
• Use a compact plane for the switch node (SW) to improve
• Use planes for V
• Flood all unused areas on all layers with copper. Flood-
When laying out a printed circuit board without a ground
plane, use the following checklist to ensure proper opera-
tion of the controller. These items are also illustrated in
Figure 7.
• Segregate the signal and power grounds. All small-
• Connect the input capacitor(s), C
• Keep the high dV/dT SW, BOOST and TG nodes away
• Connect the INTV
• Connect the top driver boost capacitor, C
• Connect the V
cooling of the MOSFETs and to keep EMI down.
filtering and to keep power losses low.
ing with copper reduces the temperature rise of power
components. Connect these copper areas to any DC
net (V
system).
signal components should return to the SGND pin at
one point, which is then tied to the PGND pin.
This capacitor carries the MOSFET AC current.
from sensitive small-signal nodes.
to the INTV
the BOOST and SW pins.
to the V
IN
IN
, V
and PGND pins.
OUT
CC
and PGND pins.
, GND or to any other DC rail in your
IN
IN
CC
pin decoupling capacitor, C
and V
decoupling capacitor, C
OUT
to maintain good voltage
IN
, close to the IC.
LTC3609
B
VCC
, closely to
F
, closely
, closely

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