AAT2847IML-EE-T1 Advanced Analog Technology, Inc., AAT2847IML-EE-T1 Datasheet - Page 16

• Manufacturer Part Number: AAT2847IML-EE-T1
• Description: Four-Channel Backlight Driver with Dual LDOs
• Manufacturer: Advanced Analog Technology, Inc.

Before choosing a particular capacitor, verify the capaci-
tor’s performance with the characteristics illustrated in
the component’s data sheet. Performance verification
will help avoid undesirable component related perfor-
mance deficiencies.
PCB Layout
To achieve adequate electrical and thermal performance,
careful attention must be given to the PCB layout. In the
worst-case operating condition, the chip must dissipate
considerable power at full load. Adequate heat-sinking
must be achieved to ensure intended operation.
Figures 5 and 6 illustrate an example PCB layout. The
bottom of the package features an exposed metal pad.
The exposed pad acts, thermally, to transfer heat from
the chip and, electrically, as a ground connection.
16
ChargePump
TM
Pin #1
Figure 4: AAT2847 Package Layout.
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Four-Channel Backlight Driver with Dual LDOs
The junction-to-ambient thermal resistance (θ
connection can be significantly reduced by following a
couple of important PCB design guidelines. The PCB area
directly underneath the package should be plated so that
the exposed paddle can be mated to the top layer PCB
copper during the reflow process. Multiple copper plated
thru-holes should be used to electrically and thermally
connect the top surface pad area to additional ground
plane(s).
The chip ground is internally connected to both the
exposed pad and to the AGND and PGND pins. It is good
practice to connect the GND pins to the exposed pad
area with traces as shown in Figure 4.
The flying capacitors (C1 and C2), input capacitor (C4),
and output capacitors (C3, C5, and C6) should be con-
nected as close as possible to the IC. In addition to the
external passive components being placed as close as
possible to the IC, all traces connecting the AAT2847
should be as short and wide as possible to minimize path
resistance and potential coupling.
PRODUCT DATASHEET
AAT2847
2847.2008.05.1.2
JA
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