DocID15470 Rev 3

17/28

LD39050

Application information

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Regarding to the adjustable version, the output voltage can be adjusted from 0.8 V up to the

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

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

sensing.

The resistor divider should be selected using the following equation:

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

Ω to 50 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 reaches

approximately 160 °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 board without

damaging the device.

A good PC board layout should be used to maximize the power dissipation. The thermal

path for the heat generated by the device 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

acts as a heat sink. The 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 improve the overall thermal performance of the device.

The power dissipation of the device depends on the input voltage, output voltage and output

current, and is given by:

The junction temperature of the device is:

where:

Figure 36. Application schematic for adjustable version