DocID14492 Rev 3

19/30

ST1L05

Application information

30

Regarding to the adjustable version, the output voltage can be adjusted from 1.22 V up to

the input voltage, minus the voltage drop across PMOS (dropout voltage), by connecting a

resistor divider between ADJ pin and the output, thus allowing remote voltage sensing. The

resistor divider should be selected according to the following equation:

Equation 1

Resistors should be used with values in the range from 10 k

Ω to 100 kΩ. Lower values can

also be suitable, but they increase current consumption.

6.1

Power dissipation

An internal thermal feedback loop disables the output voltage if the die temperature rises to

approximately 165 °C. This feature protects the device from excessive temperature and

allows the user to push the limits of the power handling capability of a given circuit board

without risk of damaging the device.

A good PC board layout should be used to maximize the power dissipation. Thermal path

goes from the die to the copper lead frame through the package leads and exposed pad to

the PC board copper. The PC board copper works as a heatsink. Footprint copper pads

should be as wider as possible to spread and dissipate the heat to the surrounding ambient.

Feed-through vias to inner or backside copper layers are also useful to improve the overall

thermal performance of the device.

Power dissipation of the device depends on the input voltage, output voltage and output

current, and is given by:

Equation 2

Figure 27. ST1L05C application schematic

GND

C

O

C

I

V

I

GND

OFF ON

EN

V

O

V

O

V

O_SENSE

ST1L05C

V

I

GND

C

O

C

I

V

I

GND

OFF ON

EN

V

O

V

O

V

O_SENSE

ST1L05C

V

I