IR3897MTRPBF International Rectifier, IR3897MTRPBF Datasheet - Page 37

• Manufacturer Part Number: IR3897MTRPBF
• Description: 4A Highly Integrated Single-Input Voltage, Synchronous Buck Regulator in a PQFN package.
• Manufacturer: International Rectifier

Specifications of IR3897MTRPBF

• Part Status: Active and Preferred
• Package: PQFN / 4 x 5
• Circuit: Single Output
• Iout (a): 4
• Switch Freq (khz): 0 - 1500
• Input Range (v): 1.0 - 16
• Output Range (v): 0.5 - 12
• Pbf: PbF Option Available

Compensation parts
should be placed
as close as possible
to the Comp pin
Resistor Rt and Vref
decoupling cap should
be placed as close as
possible to their pins
LAYOUT RECOMMENDATIONS
The layout is very important when designing high
frequency switching converters. Layout will affect noise
pickup and can cause a good design to perform with less
than expected results.
Make the connections for the power components in the
top layer with wide, copper filled areas or polygons. In
general, it is desirable to make proper use of power planes
and polygons for power distribution and heat dissipation.
The inductor, output capacitors and the IR3897 should be
as close to each other as possible. This helps to reduce the
EMI radiated by the power traces due to the high switching
currents through them. Place the input capacitor directly
at the PVin pin of IR3897.
The feedback part of the system should be kept away from
the inductor and other noise sources.
37
FEBRUARY 02, 2012 |DATA SHEET | Rev 3.2
Figure 46a: IRDC3897 Demo board Layout Considerations – Top Layer
Single‐Input Voltage, Synchronous Buck Regulator
- 37 -
4A Highly Integrated SupIRBuck
The critical bypass components such as capacitors for Vin,
Vcc and Vref should be close to their respective pins. It is
important to place the feedback components including
feedback resistors and compensation components close to
Fb and Comp pins.
In a multilayer PCB use one layer as a power ground plane
and have a control circuit ground (analog ground), to which
all signals are referenced. The goal is to localize the high
current path to a separate loop that does not interfere
with the more sensitive analog control function. These two
grounds must be connected together on the PC board
layout at a single point. It is recommended to place all
the compensation parts over the analog ground plane in
top layer.
The Power QFN is a thermally enhanced package. Based on
thermal performance it is recommended to use at least a
4‐layers PCB. To effectively remove heat from the device
the exposed pad should be connected to the ground plane
using vias. Figures 46a‐d illustrates the implementation of
the layout guidelines outlined above, on the IRDC3897 4‐
layer demo board.
TM
Enough copper &
minimum ground length
path between Input and
Output
All bypass caps
should be placed
as close as possible
to their connecting pins
SW node copper is
kept only at the top
layer to minimize
the switching noise
IR3897
PD‐97663