AOZ1282CI
The power dissipation in Schottky can be approximated
as:
Several layout tips are listed below for the best electric
and thermal performance.
P
= I 1 – D V
O FW_Schottky
1. The input capacitor should be connected as close as
possible to the VIN pin and the GND pin.
diode_loss
2. The inductor should be placed as close as possible
to the LX pin and the output capacitor.
where,
V
is the Schottky diode forward voltage drop.
FW_Schottky
3. Keep the connection of the schottky diode between
the LX pin and the GND pin as short and wide
as possible.
The power dissipation of inductor can be approximately
calculated by output current and DCR of inductor.
2
4. Place the feedback resistors and compensation
components as close to the chip as possible.
P
= I R
1.1
inductor
inductor_loss
O
5. Keep sensitive signal traces away from the LX pin.
The actual junction temperature can be calculated with
power dissipation in the AOZ1282CI and thermal
impedance from junction to ambient.
6. Pour a maximized copper area to the VIN pin, the
LX pin and especially the GND pin to help thermal
dissipation.
P
–P
total_loss diode_loss inductor_loss
--------------------------------------------------------------------------------------------------------------------------
=
–P
T
7. Pour a copper plane on all unused board area and
connect the plane to stable DC nodes, like VIN,
GND or VOUT.
junction
+ T
JA
ambient
The maximum junction temperature of AOZ1282CI is
150ºC, which limits the maximum load current capability.
The thermal performance of the AOZ1282CI is strongly
affected by the PCB layout. Extra care should be taken
by users during design process to ensure that the IC will
operate under the recommended environmental
conditions.
Rev. 0.5 September 2012
www.aosmd.com
Page 10 of 13
AOS [ ALPHA & OMEGA SEMICONDUCTORS ]
