TS5205_07 Datasheet, PDF (5/7 Pages) Taiwan Semiconductor Company, Ltd – 150mA Low Noise LDO Voltage Regulator with Enable Function

TS5205
150mA Low Noise LDO Voltage Regulator
with Enable Function
Application Information (Continue)
Dual Supply Operation
When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must
be diode clamped to ground.
Thermal Characteristics
TS5205 series is designed to provide 150mA (5V version) 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^oC), 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 Pd(max) for Pd 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 TS5205CX33 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^oC – 25^oC) / 220^oC/W
P_D(MAX) = 455mW
The junction to ambient thermal resistance for the minimum footprint is 220^oC/W, the maximum power dissipation
must not be exceeded for proper operation. Using the output voltage of 3.3V and an output current of 120mA, the
maximum input voltage can be determined. From the electrical characteristics table, the maximum ground current for
120mA output current is 2.5mA.
445mW = (V_IN – 3.3V) * 150mA + V_IN * 2.5mA
445mW = V_IN * 150mA – 3.3 * 150mA + V_IN * 2.5mA
445mW = V_IN * 150mA – 495mW + V_IN * 2.5mA
950mW = V_IN * 152.5mA
V_IN(max) = 6.23V
Therefore, a 3.3V application at 150mA of output current can accept a maximum input voltage of 6.23V in a SOT-25
package.
Fixed Output Regulator Design
TS5205CX5xx
V_IN
V_OUT
TS5205CX5xx
V_IN
V_OUT
C_OUT
2.2uF
C_BYP
470pF
Ultra Low Noise Fixed Voltage Application
Includes a 470pF capacitor for low noise operation and
shows EN connected to IN for an application where
enable/shutdown is not required. C_OUT= 2.2uF minimum.
EN
on
off
C_OUT
2.2uF
Low Noise Fixed Voltage Application
An example of a low noise configuration where
bypass is not required. C_OUT= 2.2uF minimum
5/7
Version: B07