lx1701 Microsemi Corporation, lx1701 Datasheet - Page 17

• Manufacturer Part Number: lx1701
• Description: 2w Filterless Mono Class-d Audio Amplifier
• Manufacturer: Microsemi Corporation

Copyright © 2004
Rev. 1.0b, 2005-04-29
T
There are two types of on-board thermal PAD design, one
is using thermal vias to sink the heat to the other layer with
metal traces. Based on Jedec Specification JESD 51-5, the
thermal vias should be designed like Figure 7. Another one
is the no via thermal PAD which is using the same side
copper PAD as heatsink, this type of thermal PAD is good
for two layer board, since the bottom side is filled with all
other kinds of trace also, it’s hard to use the whole plane for
the heatsink. But you still can use vias to sink the heat to
the bottom layer by the metal traces, then layout a NMSD
on which a metal heatsink is put to sink the heat to the
air.
HERMAL
Package Land Pattern
Micro Lead Quad
TM
Figure 7 – Comparison of land pattern theory
P
AD
V
IA
D
11861 Western Avenue, Garden Grove CA. 92841 714-898-8121, FAX [phone]
ESIGN
P C B D E S I G N G U I D E L I N E S ( C O N T I N U E D )
Layer Board with Vias
Land Pattern for Four
Integrated Products Division
®
Microsemi
For LX1701 with MLPQ-4x4 16Lds p ackage, which has
θjA =38.1°C/W by package itself, with maximum 2W
(@4ohm) output it only has 300mW power dispassion
(assuming 85% efficiency), which only has 11.4°C
temperature rise. So the non-via type thermal PAD is
suggested.
minimum gap
Maximum
2.50mm
0.15mm
2W Filterless Mono Class-D Audio Amplifier
0.3mm Dia.
Figure 8 – Recommended Land Pad with Vias for LQ16
Top View
P
RODUCTION
1 - 1.2mm
D
ATA
0.05mm minimum
0.5mm
S
0.28mm
0.15mm minimum
HEET
0.37mm Nominal
Thermal Via
Pin 1 Indicator
(bottom of Package)
Package Pad
PCB Land
LX1701
Page 17