EN5394QI Просмотр технического описания (PDF) - Enpirion, Inc.
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EN5394QI Datasheet PDF : 19 Pages
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Layout Recommendations
EN5394QI
− RA and RB are voltage
programming resistors.
− CA is used for loop
compensation.
− CSS is the soft-start
capacitor.
− AGND via is also a test point.
− Test point added for EAOUT.
− CIN can also be 2x22µF for
improved noise/EMI.
Figure 8: Critical Components and Layer 1 Copper for Minimum Footprint
Figure 8 above shows critical components and
layer 1 traces of the recommended EN5394
layout for minimum footprint with ENABLE tied
to VIN. Alternate ENABLE configurations, and
other small signal pins need to be connected
and routed according to specific customer
application. Please see the Gerber files on the
Enpirion website www.enpirion.com for exact
dimensions and other layers.
Recommendation 1: Input and output filter
capacitors should be placed on the same side
of the PCB, and as close to the EN5394QI
package as possible. They should be
connected to the device with very short and
wide traces. Do not use thermal reliefs or
spokes when connecting the capacitor pads to
the respective nodes. The +V and GND traces
between the capacitors and the EN5394QI
should be as close to each other as possible
so that the gap between the two nodes is
minimized, even under the capacitors.
Recommendation 2: The system ground
plane referred to in recommendations 2 and 3
should be the first layer immediately below the
surface layer. This ground plane should be
continuous and un-interrupted below the
converter and the input/output capacitors.
Recommendation 3: The large and small
thermal pads underneath the component must
be connected to the system ground plane
through as many vias as possible. The drill
diameter of the vias should be 0.33mm, and
the vias must have at least 1 oz. copper plating
on the inside wall, making the finished hole
size around 0.20-0.26mm. Do not use thermal
reliefs or spokes to connect the vias to the
ground plane. This connection provides the
path for heat dissipation from the converter.
Please see figures: 8, 11, and 12.
Recommendation 4: Multiple small vias (the
same size as the thermal vias discussed in
recommendation 3) should be used to connect
ground terminal of the input capacitor and
output capacitors to the system ground plane.
It is preferred to put these vias along the edge
of the GND copper closest to the +V copper.
These vias connect the input/output filter
capacitors to the GND plane, and help reduce
parasitic inductances in the input and output
current loops.
Recommendation 5: AVIN is the power supply
for the small-signal control circuits. It should be
connected to the input voltage at a quiet point.
In Figure 8 this connection is made at the input
capacitor.
Recommendation 6: The layer 1 metal under
©Enpirion 2009 all rights reserved, E&OE
03738
15
8/21/2009
www.enpirion.com
Rev:B
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