SC563

4

Example

A SC563LH is used to provide outputs of 3.3V, 50mA

from LDO and .8V, 250mA from LDO2. The input

voltage is 4.2V for LDO and 2.5V for LDO2, and the

ambient temperature of the system is 60°C.

P

= 0.3W

and

T

This calculation shows the junction temperature is 87.9°C

and it is below the maximum junction temperature of

25°C for this power dissipation. This example also dem-

onstrates that with separate input voltages for LDO and

LDO2, the total power dissipation can be reduced with

the lower LDO output voltage fed by a lower input

voltage.

Applications Information (continued)

Layout Considerations

The diagram in Figure 3 below illustrates proper layout of

a circuit. The layout considerations are listed below:

Attach the thermal pad of the device to a copper

pad with vias connected to the GND plane. This

enables better heat transfer from the device to

the PCB.

Place the input and output capacitors close to

the device for optimal transient response and

device behavior. Extra copper trace length

between the device input and output to the

capacitor soldering pad introduces parasitic

inductance.

Connect all ground connections of the input

and output capacitor directly to the ground

plane whenever possible to minimize ground

potential differences on the PCB. Shown in the

evaluation board layout below, the SC563

thermal pad, ground pins, and the input and

output capacitors are all connected to the

ground plane through vias .

•

•

•

Figure 3 — SC563 Layout Example