L6932

8/11

The thermal resistance junction to ambient of the demoboard is approximately 62°C/W. This mean that, consid-

ering an ambient temperature of 60°C and a maximum junction temperature of 150°C, the maximum power that

the device can handle is 1.5W.

This means that the device is able to deliver a DC output current of 2A only with a very low dropout.

In many applications, high output current pulses are required. If their duration is shorter than the thermal con-

stant time of the board, the thermal impedance (not the thermal resistance) has to be considered.

In figure 10 the thermal impedance versus the duration of the current pulse for the SO(4+2+2) mounted on board

is shown.

Figure 10. Thermal Impedance

Considering a pulse duration of 1sec, the thermal impedance is close to 20°C/W, allowing much bigger power

dissipated.

Example:

Vin = 3.3V

Vout = 1.8V

Iout = 2A

Pulse Duration = 1sec

The power dissipated by the device is:

Considering a thermal impedance of 20°C/W, the maximum junction temperature will be:

Obviously, with pulse durations longer than approximately 10sec the thermal impedance is very close to the

thermal resistance (60°C/W to 70°C/W).