LMV321M5X National Semiconductor, LMV321M5X Datasheet - Page 11

• Manufacturer Part Number: LMV321M5X
• Description: IC,Operational Amplifier,SINGLE,BICMOS,TSOP,5PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LMV321M5X

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Notes
In Figure 3 , the isolation resistor R
C
margin to the overall system. The desired performance de-
pends on the value of R
value, the more stable Vout will be. Figure 4 is an output
waveform of Figure 3 using 620
C
The circuit in Figure 5 is an improvement to the one in Figure
3 because it provides DC accuracy as well as AC stability. If
there were a load resistor in Figure 3 , the output would be
voltage divided by R
ure 5 , R
techniques to connect V
ing the value of R
LMV321/358/324. C
of phase margin by feeding the high frequency component of
the output signal back to the amplifier’s inverting input,
thereby preserving phase margin in the overall feedback
loop. Increased capacitive drive is possible by increasing the
value of C
FIGURE 3. Indirectly Driving A Capacitive Load Using
L
L.
FIGURE 4. Pulse Response of the LMV324 Circuit in
.
form a pole to increase stability by adding more phase
F
provides the DC accuracy by using feed-forward
F
. This in turn will slow down the pulse response.
F
Resistive Isolation
ISO
F
due to the input bias current of the
and R
and the load resistor. Instead, in Fig-
IN
Time (2 s/div)
Figure 3
ISO
to R
ISO
. The bigger the R
L
. Caution is needed in choos-
(Continued)
serve to counteract the loss
ISO
for R
and the load capacitor
ISO
DS100060-4
and 510 pF for
DS100060-99
ISO
resistor
11
3.0 Input Bias Current Cancellation
The LMV321/358/324 family has a bipolar input stage. The
typical input bias current of LMV321/358/324 is 15 nA with
5V supply. Thus a 100 k input resistor will cause 1.5 mV of
error voltage. By balancing the resistor values at both invert-
ing and non-inverting inputs, the error caused by the ampli-
fier’s input bias current will be reduced. The circuit in Figure
6 shows how to cancel the error caused by input bias
current.
4.0 Typical Single-Supply Application Circuits
4.1 Difference Amplifier
The difference amplifier allows the subtraction of two volt-
ages or, as a special case, the cancellation of a signal com-
mon to two inputs. It is useful as a computational amplifier, in
making a differential to single-ended conversion or in reject-
ing a common mode signal.
FIGURE 6. Cancelling the Error Caused by Input Bias
FIGURE 5. Indirectly Driving A Capacitive Load with
DC Accuracy
Current
DS100060-6
DS100060-5
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