NCS2002(2004) 查看數據表（PDF） - ON Semiconductor

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NCS2002
(Rev.:2004)

Sub-One Volt Rail-to-Rail Operational Amplifier with Enable Feature

ON Semiconductor 

NCS2002, NCV2002

Output

The output stage consists of complimentary P and N

channel devices connected to provide rail−to−rail output

drive. With a 2.0 k load, the output can swing within 50 mV

of either rail. It is also capable of supplying over 75 mA

when powered from 5.0 V and 1.0 mA when powered from

0.9 V.

When connected as a unity gain follower, the NCS2002

can directly drive capacitive loads in excess of 820 pF at

room temperature without oscillating but with significantly

reduced phase margin. The unity gain follower

configuration exhibits the highest bandwidth and is most

prone to oscillations when driving a high value capacitive

load. The capacitive load in combination with the

amplifier’s output impedance, creates a phase lag that can

result in an under−damped pulse response or a continuous

oscillation. Figure 35 shows the effect of driving a large

capacitive load in a voltage follower type of setup. When

driving capacitive loads exceeding 820 pF, it is

recommended to place a low value isolation resistor

between the output of the op amp and the load, as shown in

Figure 34. The series resistor isolates the capacitive load

from the output and enhances the phase margin. Refer to

Figure 36. Larger values of R will result in a cleaner output

waveform but excessively large values will degrade the

large signal rise and fall time and reduce the output

amplitude. Depending upon the capacitor characteristics,

the isolation resistor value will typically be between 50 to

500 W. The output drive capability for resistive and

capacitive loads is shown in Figures 2, 3, and 23.

Input

+

−

R

Output

CL

Isolation resistor R = 50 to 500

Figure 34. Capacitance Load Isolation

Note that the lowest phase margin is observed at cold

temperature and low supply voltage.

Enable Pin

The enable pin allows the user to externally control the

device. if the enable pin is pulled below the input disable

threshold voltage (VEN < 45% VCC), the amplifier is

disabled. Once the enable pin is taken above the threshold

voltage (VEN = 60% VCC), the amplifier will turn on. In the

event the enable pin is not connected, the amplifier will

remain on by default

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