LM5152BCN National Semiconductor, LM5152BCN Datasheet - Page 8

• Manufacturer Part Number: LM5152BCN
• Description: Dual and Quad High Speed/Low Power 75 MHz GBW Rail-to-Rail I/O Operational Amplifiers
• Manufacturer: National Semiconductor

www.national.com
Typical Performance
Characteristics
Application Information
The LM6152/6154 is ideally suited for operation with about
10k
negative input terminal.
With R
close loop gain of 10 or less, an additional small compensa-
tion capacitor (C
in order to achieve a reasonable overshoot (10%) at the out-
put by compensating for stray capacitance across the inputs.
The optimum value for C
mentally with a trimmer cap in place since its value is depen-
dant on the supply voltage, output driving load, and the oper-
ating gain. Below, some typical values used in an inverting
configuration and driving a 10k
for reference:
In the non-inverting configuration, the LM6152/6154 can be
used for closed loop gains of +2 and above. In this case,
also, the compensation capacitor (C
across R
Volts
FIGURE 1. Typical Inverting Gain Circuit A
V
24
3
(Feedback Resistor, R
S
F
TABLE 1. Typical BW (−3 dB) at Various
set to this value, for most applications requiring a
F
( = 10 k ) for gains of 10 or less.
Total Harmonic Distortion
Supply Voltage and Gains
F
−100
−100
) (see Figure 1 ) is recommended across R
Gain
−10
−10
−1
−1
vs. Frequency
F
(Continued)
can best be established experi-
F
) between the output and the
None
None
5.6
6.8
2.2
4.7
C
pF
F
load have been tabulated
DS012350-31
F
DS012350-30
) is recommended
BW (−3 dB)
0.797
0.962
MHz
1.97
6.6
2.2
V
4
= −1
F
8
Because of the unique structure of this amplifier, when used
at low closed loop gains, the realizable BW will be much less
than the GBW product would suggest.
The LM6152/6154 brings a new level of ease of use to op
amp system design.
The greater than rail-to-rail input voltage range eliminates
concern over exceeding the common-mode voltage range.
The rail-to-rail output swing provides the maximum possible
dynamic range at the output. This is particularly important
when operating on low supply voltages.
The high gain-bandwidth with low supply current opens new
battery powered applications where higher power consump-
tion previously reduced battery life to unacceptable levels.
The ability to drive large capacitive loads without oscillating
functional removes this common problem.
To take advantage of these features, some ideas should be
kept in mind.
The LM6152/6154, capacitive loads do not lead to oscilla-
tions, in all but the most extreme conditions, but they will re-
sult in reduced bandwidth. They also cause increased set-
tling time.
Unlike most bipolar op amps, the unique phase reversal
prevention/speed-up circuit in the input stage, caused the
slew rate to be very much a function of the input pulse ampli-
tude. This results in a 10 to 1 increase in slew rate when the
differential input signal increases. Large fast pulses will raise
the slew-rate to more than 30V/µs.
The speed-up action adds stability to the system when driv-
ing large capacitive loads.
A conventional op amp exhibits a fixed maximum slew-rate
even though the differential input voltage rises due to the
lagging output voltage. In the LM6152/6154, increasing lag
causes the differential input voltage to increase but as it
does, the increased slew-rate keeps the output following the
input much better. This effectively reduces phase lag. As a
result, the LM6152/6154 can drive capacitive loads as large
as 470 pF at gain of 2 and above, and not oscillate.
Capacitive loads decrease the phase margin of all op amps.
This can lead to overshoot, ringing and oscillation. This is
caused by the output resistance of the amplifier and the load
capacitance forming an R-C phase shift network. The
LM6152/6154 senses this phase shift and partly compen-
sates for this effect.
FIGURE 2. Slew Rate vs. V
DS012350-21
diff