TS5213
Taiwan Semiconductor
Document Number: DS_P0000201 5 Version: G15
APPLICATION INFORMATION (CONTINUE)
Thermal Characteristics
TS5213 series is designed to provide 80mA of continuous current in a very small package. Maximum power
dissipation can be calculated based on the output current and the voltage drop across the part. To determine the
maximum power dissipation of the package, use the junction-ambient thermal resistance of the device and the
following basic equation:
P
D(MAX)
= [ T
J(MAX)
– T
A
] /Θ
JA
T
J(MAX)
is the maximum junction temperature of the die(125
o
C), and Ta is the ambient operating temperature. Θ
JA
is layout dependent, the actual power dissipation of the regulator circuit can be determined using the equation:
P
D
= (V
IN
– V
OUT
) * I
OUT
+ V
IN
* I
GND
Substituting P
D(MAX)
for P
D
and solving for the operating conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit. For example, when operating the TS5213CX550 at room
temperature with a minimum footprint layout, the maximum input voltage for a set output current can be
determined as follows:
P
D(MAX)
= (125
o
C – 25
o
C) / 220
o
C/W
P
D(MAX)
= 455mW
The junction to ambient thermal resistance for the minimum footprint is 220
o
C/W, the maximum power dissipation
must not be exceeded for proper operation. Using the output voltage of 5.0V and an output current of 80mA, the
maximum input voltage can be determined. Form the electrical characteristics table, the maximum ground
current for 80mA output current is 1mA.
445mW = (V
IN
– 5.0V ) * 80mA + V
IN
* 1.8mA
445mW = V
IN
* 80mA – 5.0 * 80mA + V
IN
* 1.8mA
445mW = V
IN
* 80mA – 400mW + V
IN
* 1.8mA
845mW = V
IN
* 81.8mA
V
IN
(max) = 10.33V
Therefore, a 5.0V application at 80mA of output current can accept a maximum input voltage of 10.33V in a SOT-
25 package.
