Datasheet

Power Dissipation www.ti.com
Figure 3. V
OUT
vs V
EN
The Enable pin has no internal default bias and must not be left floating. The Enable pin must be actively
driven to the appropriate voltage level. In applications where the LP38513TJ is operated continuously the
Enable pin can be connected directly to V
IN
. The LP38513TJ-ADJ Evaluation board is assembled with a
10 kΩ resistor (R3) to provide pull-up to V
IN
.
Figure 4. Enable Thresholds
7 Power Dissipation
The TO-263 THIN package alone has a junction to ambient thermal resistance (θ
JA
) rating of 67°C/W.
When mounted on the LP38513TJ-ADJ Evaluation Board the θ
JA
rating is approximately 35°C/W.
Although there is only approximately 0.20 square inches (0.45in x 0.45in) of 1 ounce copper area
immediately under the package body, the top copper surface area is extended to additional copper area
on the bottom of the board by fifteen thermal vias.
With the 35°C/W thermal rating the LP38513TJ-ADJ evaluation board will dissipate a maximum of 2.8W
with T
A
= 25°C.
For a comparison of the TO-263 THIN package to the standard TO-263 package see AN-1797 TO-263
THIN Package (SNVA328).
4
AN-1670 LP38513TJ-ADJ Evaluation Board SNVA264B–January 2009–Revised April 2013
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