TS39100_07 Datasheet, PDF (7/13 Pages) Taiwan Semiconductor Company, Ltd – 1A Ultra Low Dropout Voltage Regulator with Multi-Function

TS39100/1/2/3/4/5
1A Ultra Low Dropout Voltage Regulator
with Multi-Function
Application Information (Continue)
Transient Response and 3.3V to 2.5V or 2.5V to 1.8V Conversion
TS39100/1/2/3/4/5 has excellent transient response to variations in input voltage and load current. The device have
been designed to respond quickly to load current variations and input voltage variations. Large output capacitors are
not required to obtain this performance. A standard 10uF output capacitor, preferably tantalum, is all that is required.
Larger values help to improve performance even further. By virtue of its low dropout voltage, this device does not
saturate into dropout as readily as similar NPN base designs. When converting from 3.3V to 2.5V or 2.5V to 1.8V, the
NPN based regulators are already operating in dropout, with typical dropout requirements of 1.2V or greater,. To
convert down to 2.5V or 1.8V without operating in dropout, NPN based regulators require an input voltage of 3.7V at
the very least. The TS3910x regulator will provide excellent performance with an input as low as 3.0V or 2.5V
respectively. This gives the PNP based regulators a distinct advantage over older, NPN based linear regulators.
Power Dissipation
From under curves, the minimum area of copper necessary for the par to operate safely can be determined. The
maximum allowable temperature rise must be calculated to determine operation along which curve.
Copper area lay out information
Determine the power dissipation requirements for the design along with the maximum ambient temperature at which
the device will be operated. Refer to power dissipation with copper area curve, which shows safe operating curves for
three different ambient temperatures with 25^oC, 50^oC, 85^oC. From these curves, the minimum amount of copper can
be determined by knowing the maximum power dissipation required.
P_D = (V_IN- V_OUT) * I_OUT + V_IN * I_GND
If we used a 5.0V output device and a 6V input at an output current of 350mA, then the power dissipation is as follows:
P_D = (6.0V- 5.0V) * 350mA + 5V * 4mA
P_D = 350mW + 20mW
P_D = 370mW
If the maximum ambient temperature is 85^oC and the power dissipation is as above 375mW, the curve is shows that
the required area of copper is 80mm².
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Version: B07