Datasheet

TS982 Application information
Doc ID 9557 Rev 7 15/21
3.3 Thermal management benefits
A good thermal design is important to maintain the temperature of the silicon junction below
T
j
= 150 °C as given in the absolute maximum ratings and also to maintain the operating
power level.
Another effect of temperature is that the life expectancy of an integrated circuit decreases
exponentially when operating at high temperature over an extended period of time. It is
estimated that, the chip failure rate doubles for every 10 to 20 °C. This demonstrates that
reducing the junction temperature is also important to improve the reliability of the amplifier.
Because of the high dissipation capability of the SO-8 exposed-pad package, the dual
op amp TS982 has a lower junction temperature for high current applications in high
ambient temperatures.
3.4 Thermal management guidelines
The following guidelines are a simple procedure to determine the PCB you should use in
order to get the best from the SO-8 exposed-pad package:
1. Determine the total power P
total
to be dissipated by the IC.
P
total
= I
CC
x V
CC
+ V
drop1
x I
out1
+ V
drop2
x I
out2
I
CC
x V
CC
is the DC power needed by the TS982 to operate with no load. Refer to
Figure 1: Current consumption vs. supply voltage on page 7 to determine I
CC
versus
V
CC
and versus temperature.
The other terms are the power dissipated by the two operators to source the load. If the
output signal can be assimilated to a DC signal, you can calculate the dissipated power
using the voltage drop curves versus output current, supply voltage, and temperature
(Figure 2 on page 7 to Figure 8 on page 8).
2. Specify the maximum operating temperature, (T
a
) of the TS982.
3. Specify the maximum junction temperature (T
j
) at the maximum output power. As
discussed above, T
j
must be below 150 °C and as low as possible for reliability
considerations.
Therefore, the maximum thermal resistance between junction and ambient R
thja
is:
R
thja
= (T
j
- T
a
)/P
total
Different PCBs can give the right R
thja
for a given application. Figure 42 gives the R
thja
of the
SO-8 exposed pad versus the copper area of a top side PCB.