aoz1905 Alpha & Omega Semiconductor, aoz1905 Datasheet - Page 10

• Manufacturer Part Number: aoz1905
• Description: Ezboost 2a General Purpose Regulator
• Manufacturer: Alpha & Omega Semiconductor

T
In PCB layout, minimizing the two loops area reduces the
noise of this circuit and improves efficiency. A ground
plane is recommended to connect input capacitor, output
capacitor, and GND pin of the AOZ1905.
In the AOZ1905 boost regulator circuit, the three major
power dissipating components are the AOZ1905 and
output inductor. The total power dissipation of converter
circuit can be measured by input power minus output
power.
The power dissipation of inductor can be approximately
calculated by input current and DCR of inductor.
The power dissipation in the diode can be calculated as:
where;
V
The actual AOZ1905 junction temperature can be
calculated with power dissipation in the AOZ1905 and
thermal impedance from junction to ambient.
P
P
P
FW
junction
Rev. 1.4 May 2008
diode_loss
total _loss
inductor _loss
is the forward voltage drop of the diode.
=
=
=
P
V
I
=
total _loss
O
IN
+
(a) MSOP-8
I
I N
T
ambient
I
1 D
2
IN
–
R
–
–
P
inductor
V
inductor _loss
O
V
FW
I
O
1.1
Figure 3. AOZ1905 PCB Layout Example
–
P
diode_loss
www.aosmd.com
The maximum junction temperature of AOZ1905 is
145°C, which limits the maximum load current capability.
The thermal performance of the AOZ1905 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.
Several layout tips are listed below for the best electric
and thermal performance. Figure 2 below illustrates the
PCB layout example as reference.
1. Do not use thermal relief connection to the V
2. A ground plane is preferred.
3. Make the current trace from LX pins to L to Co to the
4. Pour copper plane on all unused board area and
5. Keep sensitive signal trace such as trace connected
the GND pin. Pour a maximized copper area to the
GND pin and the V
GND as short as possible.
connect it to stable DC nodes, like V
with FB pin and COMP pin far away from the LX pin.
(a) DFN-10 3x3
IN
pin to help thermal dissipation.
IN
, GND or V
AOZ1905
Page 10 of 16
IN
and
OUT
.