RT9519A RICHTEK [Richtek Technology Corporation], RT9519A Datasheet - Page 16

• Manufacturer Part Number: RT9519A
• Description: Linear Single Cell Li-lon Battery Charger with Auto Power Path Management
• Manufacturer: RICHTEK [Richtek Technology Corporation]

RT9519A
Thermal Considerations
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
P
where T
the ambient temperature, and θ
thermal resistance.
For recommended operating condition specifications of
the RT9519A, the maximum junction temperature is 125°C
and T
thermal resistance, θ
20L 3x3 packages, the thermal resistance, θ
W on a standard JEDEC 51-7 four-layer thermal test board.
The maximum power dissipation at T
calculated by the following formula :
P
WQFN-20L 3x3 package
The maximum power dissipation depends on the operating
ambient temperature for fixed T
resistance, θ
curve in Figure 3 allows the designer to see the effect of
rising ambient temperature on the maximum power
dissipation.
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16
D(MAX)
D(MAX)
A
is the ambient temperature. The junction to ambient
= (T
J(MAX)
= (125°C − 25°C) / (68°C/W) = 1.471W for
J(MAX)
JA
is the maximum junction temperature, T
. For the RT9519A package, the derating
− T
A
JA
) / θ
, is layout dependent. For WQFN-
JA
JA
is the junction to ambient
J(MAX)
A
= 25°C can be
and thermal
JA
, is 68°C/
A
is
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Figure 3. Derating Curves for RT9519A Package
0
25
Ambient Temperature (°C)
50
DS9519A-02 April 2011
75
Four-Layer PCB
100
125