Datasheet

LD49150XX08, LD49150XX10, LD49150XX12 Application hints
Doc ID 13446 Rev 3 15/22
8.8 Heatsinking PPAK package
The PPAK package uses the copper plane on the PCB as a heatsink. The tab of these
packages is soldered to the copper plane for heat sinking. It is also possible to use the PCB
ground plane a heatsink. This area can be the inner GND layer of a multi-layer PCB, or, in a
dual layer PCB, it can be an unbroken GND area on the opposite side where the IC is
situated with a dissipating area thermally connected through vias holes, filled by solder.
Figure 26 shows a curve for
θ
JA
of the PPAK package for different copper area sizes, using
a typical PCB with 1/16 in thick G10/FR4.
8.9 Adjustable regulator design
The LD49150xx adjustable version allows fixing output voltage anywhere between 0.8 V and
4.5 V using two resistors as shown in the typical application circuit. For example, to fix the
R
1
resistor value between V
OUT
and the ADJ pin, the resistor value between ADJ and GND
(R
2
) is calculated by:
R
2
= R
1
[0.8/(V
OUT
- 0.8)]
Where V
OUT
is the desired output voltage.
It is suggested to use R1 values lower than 10 kΩ to obtain better load transient
performances. Even, higher values up to 100 kΩ are suitable.
8.10 Enable
The fixed output voltage versions of LD49150xx feature an active high Enable input (EN)
that allows on-off control of the regulator. The EN input threshold is guaranteed between 0.4
V and 1.4 V, for simple logic interfacing. The regulator is set in shut down mode when V
EN
<
0.4 V and it is in operating mode (V
OUT
activated) when V
EN
> 1.4 V. If not in use, the EN pin
must be tied directly to the V
IN
to keep the regulator continuously activated. The En pin must
not be left at high impedance.
Figure 24.
θ
JA
vs. copper area for PPAK package