Datasheet

OPA452, 453
11
SBOS127C
www.ti.com
typical output current of 125mA. With ±40V power supplies,
this creates an internal dissipation of 10W. This far exceeds
practical heat sinking and is not recommended. If operation
in this region is unavoidable, use the part with a heat sink.
HEAT SINKING
Power dissipated in the OPA452 or OPA453 will cause the
junction temperature to rise. For reliable operation, the junc-
tion temperature should be limited to +125°C. Many applica-
tions will require a heat sink to assure that the maximum
operating junction temperature is not exceeded. The heat
sink required depends on the power dissipated and on
ambient conditions.
For heat sinking purposes, the tab of the DDPAK is typically
soldered directly to a circuit board copper area. Increasing
the copper area improves heat dissipation. Figure 4 shows
typical thermal resistance from junction-to-ambient as a
function of copper area.
Depending on conditions, additional heat sinking may be
required. Aavid Thermal Products Inc. manufactures sur-
face-mountable heat sinks designed specifically for use with
these packages. Further information is available on Aavid’s
web site, www.aavid.com.
FIGURE 4. DDPAK Thermal Resistance versus Circuit Board
Copper Area.
CAPACITIVE LOADS
The dynamic characteristics of the OPA452 and OPA453
have been optimized for commonly encountered gains, loads,
and operating conditions. The combination of low closed-
loop gain and capacitive load will decrease the phase margin
and may lead to gain peaking or oscillations. Figure 5 shows
a circuit that preserves phase margin with capacitive load.
Figure 6 shows the small-signal step response for the circuit
in Figure 5. Consult Application Bulletin SBOA015, at
www.ti.com, for more information.
FIGURE 5. Driving Large Capacitive Loads.
R
F
5kΩ
C
S
1.8nF
10nF
OPA452
+40V
–40V
V
I
C
F
270pF
R
G
5kΩ
THERMAL RESISTANCE vs
CIRCUIT BOARD COPPER AREA
50
40
30
20
10
0
012345
Copper Area (inches
2
)
OPA452FA, OPA453FA
Surface-Mount Package
1oz. copper
Circuit Board Copper Area
OPA452FA, OPA453FA
Surface-Mount Package
Thermal Resistance,
JA
(°C/W)
θ
FIGURE 6. Small-Signal Step Response for Figure 5.
SMALL-SIGNAL STEP RESPONSE
(G = –1, C
L
= 10nF)
20mV/div
2.5µs/div
OPA452