Datasheet
Typical Performance Characteristics T
A
=
25˚C, R
L
=
1MΩ. unless otherwise specified (Continued)
Application Information
The table below, depicts the maximum operating supply volt-
age for each package type:
TABLE 1. Maximum Supply Voltage Values
SOT23-5 SO-8
Single Supply 10V 30V
Dual Supplies
±
5V
±
15V
Stable unity gain operation is possible with supply voltage of
5V for all capacitive loads. This allows the possibility of using
the device in portable applications with low supply voltages
with minimum components around it.
Above a supply voltage of 6V (
±
3V Dual supplies), an addi-
tional resistor and capacitor (shown below) should be placed
in the feedback path to achieve stability at unity gain over the
full temperature range.
The package power dissipation should be taken into account
when operating at high ambient temperatures and/or high
power dissipative conditions. Refer to the power derating
curves in the data sheet for each type of package.
In determining maximum operable temperature of the de-
vice, make sure the total power dissipation of the device is
considered; this includes the power dissipated in the device
with a load connected to the output as well as the nominal
dissipation of the op amp.
The device is capable of tolerating momentary short circits
from its output to ground but prolonged operation in this
mode will damage the device, if the maximum allowed junc-
tion temperation is exceeded.
APPLICATION CIRCUITS
Current Boost Circuit
The circuit in
Figure 2
can be used to achieve good linearity
along with high output current capability.
By proper choice of R
3
, the LM7121 output can be set to
supply a minimal amount of current, thereby improving its
output linearity.
R
3
can be adjusted to allow for different loads:
R
3
=
0.1 R
L
The circuit above has been set for a load of 100Ω.
Reasonable speeds (
<
30 ns rise and fall times) can be ex-
pected up to 120 mA
PP
of load current (see
Figure 3
for step
response across the load).
Undistorted Output Swing
vs Frequency
DS012348-86
Total Power Dissipation
vs Ambient Temperature
DS012348-65
DS012348-87
FIGURE 1. Typical Circuit for A
V
=
+1
Operation (V
S
≥ 6V)
DS012348-92
FIGURE 2. Simple Circuit to Improve Linearity
and Output Drive Current
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