AL8808WT-7 Diodes Inc., AL8808WT-7 Datasheet - Page 15

• Manufacturer Part Number: AL8808WT-7
• Description: LED Lighting Drivers LED MV Int Switch TS Switch TSOT25 T&R 3K
• Manufacturer: Diodes Inc.

Specifications of AL8808WT-7

• Rohs: yes
• Input Voltage: 6 V to 30 V
• Operating Frequency: 1 MHz
• Maximum Supply Current: 450 uA
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Package / Case: TSOT-25
• Minimum Operating Temperature: - 40 C

Application Information
Thermal Considerations
For continuous conduction mode of operation, the absolute maximum junction temperature must not be exceeded. The maximum power
dissipation depends on several factors: the thermal resistance of the IC package (θ
between junction and ambient temperature.
The maximum power dissipation can be calculated using the following formula:
where
The major thermal path for the TSOT25 package is pin 2 (GND pin) and it is important for minimizing the θ
mass is associated with pin 2. The thermal impedance from the AL8808 junction to pin 2 is approximately 57°C/W.
The AL8808’s θ
area on bottom layer with 1oz copper standing in still air is approximately 209°C/W. Yielding a maximum power dissipation at 25°C of 0.47W
The AL8808’s θ
maximum power dissipation at 25°C of 0. 66W.
Figure 42 shows the power derating of the AL8808 on different area PCB with maximum area on bottom of PCB with 1 and 2oz copper standing in
still air.
AL8808
Document number: DS35648 Rev. 2 - 2
T
T
θ
P
J(MAX)
A
JA
( D
is the ambient temperature, and
MAX
is the junction to ambient thermal resistance.
JA
JA
)
is the maximum operating junction temperature; for the AL8808 this is +125°C.
on a 25 x 25mm double sided FR4 PCB with maximum area top and bottom with vias is approximately 151°C/W; which gives a
=
on a 25 x 25mm double sided FR4 PCB with minimum recommended pad layout on top layer and thermal vias to maximum
T
( J
MAX
θ
JA
)
−
T
A
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-40
(25mm) with 2oz Cu max area top
(25mm) with 1oz Cu min area top
(25mm) with 2oz Cu min area top
(25mm) with 1oz Cu min area top
(50mm) with 1oz Cu max area top
(50mm) with 2oz Cu max area top
(cont.)
-25
2
2
2
2
2
2
(50mm) with 1oz Cu min area top
-10
2
Figure 42. Derating Curve for Different PCB
5
AMBIENT TEMPERATURE (C)
20
www.diodes.com
15 of 20
35
50
JC
65
), PCB layout, airflow surrounding the IC, and difference
80
95
110
JA
that a suitable area and thermal
125
© Diodes Incorporated
AL8808
January 2013