Application information

LD39200

12/30

DocID025637 Rev 1

6

Application information

6.1

Thermal and short-circuit protections

The LD39200 is self-protected from short-circuit conditions and overtemperature. When the

output load is higher than the one supported by the device, the output current rises until the

limit of typically 3.5 A is reached; at this point the current is kept constant even when the

load impedance is zero. The thermal protection acts when the junction temperature reaches

170 °C. The IC enters the shutdown status. As soon as the junction temperature falls again

below 150 °C the device starts working again. In order to calculate the maximum power the

used:

Equation 1

6.2

Output voltage setting for ADJ version

In the adjustable version, the output voltage can be set from 0.5 V up to the input voltage

minus the voltage drop across the pass transistor (dropout voltage), by connecting a

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

resistor divider can be selected using the following equation:

Equation 2

6.3

Enable pin

The LD39200 features an enable function. When the EN voltage is higher than 1.2 V the

device is ON, and if it is lower than 0.5 V the device is OFF. In shutdown mode, the total

current consumption is 10 nA (typ). The EN pin does not have an internal pull-up, therefore

it cannot be left floating if it is not used.

6.4

Power Good pin (PG)

Some applications require a flag showing that the output voltage is in the correct range.

Power Good threshold depends on the output voltage. When the output voltage is higher

high impedance.