LM7121IN National Semiconductor, LM7121IN Datasheet - Page 13

• Manufacturer Part Number: LM7121IN
• Description: IC AMP FEEDBACK 235MHZ 8DIP
• Manufacturer: National Semiconductor

Specifications of LM7121IN

• Amplifier Type: Voltage Feedback
• Number Of Circuits: 1
• Slew Rate: 1300 V/µs
• Gain Bandwidth Product: 175MHz
• -3db Bandwidth: 235MHz
• Current - Input Bias: 5.2µA
• Voltage - Input Offset: 900µV
• Current - Supply: 5.3mA
• Current - Output / Channel: 71mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 33 V, ±2.25 V ~ 16.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Output Type: -
• Other names: *LM7121IN

Application Information
The table below depicts the maximum operating supply
voltage for each package type
Stable unity gain operation is possible with supply voltage of
5V for all capacitive loads This allows the possibility of us-
ing the device in portable applications with low supply volt-
ages with minimum components around it
Above a supply voltage of 6V (
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 ac-
count when operating at high ambient temperatures and or
high power dissipative conditions Refer to the power derat-
ing 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
Single Supply
Dual Supplies
TABLE I Maximum Supply Voltage Values
FIGURE 1 Typical Circuit for A
Operation (V
SOT23-5
g
10V
5V
g
S t
3V Dual supplies) an addi-
6V)
g
SO-8
30V
15V
V
e a
TL H 12348 – 87
1
g
30V
DIP
15V
13
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
supply a minimal amount of current thereby improving its
output linearity
R
The circuit above has been set for a load of 100
Reasonable speeds (
pected up to 120 mA
step response across the load)
It is very important to keep the lead lengths to a minimum
and to provide a low impedance current path by using a
ground-plane on the board
Caution If R
of LM7121 would be disturbed and it would have to supply
the full amount of load current This might damage the part
if power dissipation limit is exceeded
3
can be adjusted to allow for different loads
FIGURE 2 Simple Circuit to Improve Linearity
FIGURE 3 Waveform across a 100
L
is removed the current balance at the output
and Output Drive Current
k
PP
3
30 ns rise and fall times) can be ex-
R
3
the LM7121 output can be set to
of load current (see Figure 3 for
e
0 1 R
L
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Load
TL H 12348– 92
TL H 12348– 93
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