LP38500-ADJ_15 Datasheet, PDF (18/28 Pages) Texas Instruments – LP3850x-ADJ, LP3850xA-ADJ 1.5-A Flexcap Low-Dropout Linear Regulator for 2.7-V to 5.5-V Inputs

LP38500-ADJ, LP38502-ADJ
SNVS539H – NOVEMBER 2007 – REVISED SEPTEMBER 2015
Layout Examples (continued)
www.ti.com
EN
Pull-up
Resistor
IN
Input
Capacitor
R2
ADJ
R1
OUT
Output
Capacitor
Ground
Figure 23. LP38502-ADJ TO-263 Layout
Input
Capacitor
VIN
BYPASS
N/C
GROUND
IN
Ground
SHUTDOWN
ERROR
Error Pullup
Resistor
VOUT
SENSE
OUT
VOUT
Output
Capacitor
Figure 24. LP3850x WSON Layout
10.2.1 Heatsinking WSON Package
The junction-to-ambient thermal resistance for the WSON package is dependent on how much PCB copper is
present to conduct heat away from the device. The LP38502SD-ADJ evaluation board (980600046-100) was
tested and gave a result of about 52.5°C/W with a power dissipation of 1 W and no external airflow. This
evaluation board is a two layer board using two ounce copper, and the copper area on topside for heatsinking is
approximately two square inches. Multiple vias under the DAP also thermally connect to the backside layer which
has about three square inches of copper dedicated to heatsinking.
With four thermal vias directly under the DAP to the first copper plane, the modeling predicts a R_θJA of 52.5°C/W.
Adding a dog-bone copper area with four additional thermal vias in the dog-bone area to the first copper plane
can improve R_θJA to 45°C/W.
18
Submit Documentation Feedback
Copyright © 2007–2015, Texas Instruments Incorporated
Product Folder Links: LP38500-ADJ LP38502-ADJ