AAT1235IRN-T1 AnalogicTech, AAT1235IRN-T1 Datasheet - Page 17

• Manufacturer Part Number: AAT1235IRN-T1
• Description: High Efficiency White LED Drivers for Backlight and Keypad
• Manufacturer: AnalogicTech

SwitchReg
PCB Layout Guidelines
Boost converter performance can be adversely affected
by poor layout. Possible impact includes high input and
output voltage ripple, poor EMI performance, and
reduced operating efficiency. Every attempt should be
made to optimize the layout in order to minimize para-
sitic PCB effects (stray resistance, capacitance, and
inductance) and EMI coupling from the high frequency
SW node. A suggested PCB layout for the AAT1235 boost
converter is shown in Figures 4 and 5. The following PCB
layout guidelines should be considered:
1. Minimize the distance from Capacitor C1 and C2’s
1235.2009.09.1.2
negative terminals to the GND pins. This is espe-
cially true with output capacitor C2, which conducts
high ripple current from the output diode back to the
GND pins.
Figure 4: AAT1235 Evaluation Board
TM
Top Side Layout.
High Efficiency White LED Drivers for Backlight and Keypad
w w w . a n a l o g i c t e c h . c o m
2. Minimize the distance between L1 to D1 and switch-
3. Maintain a ground plane and connect to the IC GND
4. Consider additional PCB metal on D1’s cathode to
5. Do not connect the exposed paddle (bottom of the
ing pin SW; minimize the size of the PCB area con-
nected to the SW pin.
pin(s) as well as the GND connections of C1 and C2.
maximize heatsinking capability. This may be neces-
sary when using a diode with a high V
mal resistance.
die) to either AGND or GND because it is connected
internally to SW. Connect the exposed paddle to the
SW pin or leave floating.
Figure 5: AAT1235 Evaluation Board
Bottom Side Layout.
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AAT1235
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