Tel: 886-2-66296288
Fax: 886-2-29174598
URL: http://www.princeton.com.tw
2W × 2 Class AB Audio Power Amplifier
PT2303
HEAT DISSIPATION
During normal operation, the chip only consumes very little stand-by current. In high output power
conditions, the package temperature will rise. For proper operating temperature, a modest heat sink
mounted on the top side of the chip is required. The thermal resistance requirement of the heat sink
demand may be obtained by the formula below:
θJA
= (T
J
(max) - T
A
)/P
DISS
P
DISS
= IC dissipation power
T
J
(max) = Maximum chip conjunction temperature
T
A
= external environment temperature
θ
JA
= thermal resistance from chip conjunction to ambience environment
With 60% estimated efficiency (eff), PT2303 in 2W + 2W output power dissipation is probably
P
DISS
= ( Po ÷ eff ) - Po = 2.6W
The maximum chip conjunction temperature is 150℃, Exceed this temperature will damage the chip,
assuming the outside environment air temperature is 50℃. From the chip conjunction dissipation to
external environment thermal resistance
θ
JA
should be:
θ
JA
=
( 150 – 50 ) ÷ 2.6 = 38.4℃/W
The PT2303 chip conjunction to case thermal resistance
θ
JC
is 26℃ /W. Therefore the heat sink
thermal resistance should be:
θ
JA
-
θ
JC
= 12.4℃/W
In normal operating, PT2303 needs at least 2 sq inch PCB for heat dissipate; it should be use whole
copper foil to cover on it for enough heat dissipation space. We suggest using two-layer PCB for better
heat dissipation. The track connected to the output and power pin of IC should be as thick as possible
for better heat dissipation ability. If IC doesn’t have enough heat dissipation space (>1 sq inch), and IC
is always in full power output situation, an additional heat sink should placed on the chip.
PT2303 V1.2
-6-
December, 2007
PTC [ PRINCETON TECHNOLOGY CORP ]
