APA2030/2031
Application Descriptions
To calculate maximum ambient temperatures, first
consideration is that the numbers from the Power
Dissipation vs. Output Power graphs (page17) are
per channel values, so the dissipation of the IC heat
needs to be doubled for two-channel operation. Given
θJA, the maximum allowable junction temperature (TJ,
MAX), and the total internal dissipation (PD), the maxi-
mum ambient temperature can be calculated with the
following equation. The maximum recommended junc-
tion temperature for the APA2030/1 is 150°C. The in-
ternal dissipation figures are taken from the Power
Dissipation vs. Output Power graphs. (Page17)
power dissipation which the IC package is able to
handle can be obtained from equation13. Once the
power dissipation is greater than the maximum limit
beDd,eMcAXreased, the load impedance (RL) must be in-
creased or the ambient temperature should be
reduced.
(P
), either the supply voltage (VDD) must
Thermal Pad Considerations
The thermal pad must be connected to ground. The
package with thermal pad of the APA2030/1 requires
special attention on thermal design. If the thermal
design issues are not properly addressed, the
APA2030/1 4Ω will go into thermal shutdown when
driving a 4Ω load.
T
A,Max = TJ,Max -θϑAPD
(14)
150 - 45(0.8*2) = 78°C (TSSOP-P24)
150 - 48(0.8*2) = 73.2°C (TSSOP-P20)
The thermal pad on the bottom of the APA2030/1
should be soldered down to a copper pad on the cir-
cuit board. Heat can be conducted away from the
thermal pad through the copper plane to ambient. If
the copper plane is not on the top surface of the
circuit board, 8 to 10 vias of 13 mil or smaller in
diameter should be used to thermally couple the ther-
mal pad to the bottom plane. For good thermal
conduction, the vias must be plated through and sol-
der filled. The copper plane used to conduct heat
away from the thermal pad should be as large as
practical.
The APA2030/1 is designed with a thermal shutdown
protection that turns the device off when the junction
temperature surpasses 150°C to prevent damaging the
IC.
If the ambient temperature is higher than 25°C, a
larger copper plane or forced-air cooling will be re-
quired to keep the APA2030/1 junction temperature
below the thermal shutdown temperature (150°C).
In higher ambient temperature, higher airflow rate and/
or larger copper area will be required to keep the IC
out of thermal shutdown.
Thermal Considerations
Linear power amplifiers dissipate a significant amount
of heat in the package under normal operating
conditions.
Copyright ANPEC Electronics Corp.
23
www.anpec.com.tw
Rev. A.2 - Apr., 2004
ANPEC [ ANPEC ELECTRONICS COROPRATION ]
