NE5230NG Просмотр технического описания (PDF) - ON Semiconductor

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NE5230NG

Low voltage operational amplifier

ON Semiconductor 

NE5230, SA5230, SE5230

HALF−WAVE RECTIFIER WITH

RAIL−TO−GROUND OUTPUT SWING

Since the NE5230 input common−mode range includes

both positive and negative supply rails and the output can

also swing to either supply, achieving half−wave rectifier

functions in either direction becomes a simple task. All that

is needed are two external resistors; there is no need for

diodes or matched resistors. Moreover, it can have either

positive− or negative−going outputs, depending on the way

the bias is arranged. In Figure 9, the circuit is biased to

ground, while circuit (Figure 10) is biased to the positive

supply. This rather unusual biasing does not cause any

problems with the NE5230 because of the unique internal

saturation detectors incorporated into the part to keep the

PNP and NPN output transistors out of “hard” saturation. It

is therefore relatively quick to recover from a saturated

output condition. Furthermore, the device does not have

parasitic current draw when the output is biased to either rail.

This makes it possible to bias the NE5230 into “saturation”

and obtain half−wave rectification with good recovery. The

simplicity of biasing and the rail−to−ground half−sine wave

swing are unique to this device. The circuit gain can be

changed by the standard op amp gain equations for an

inverting configuration.

It can be seen in these configurations that the op amp

cannot respond to one−half of the incoming waveform. It

cannot respond because the waveform forces the amplifier

to swing the output beyond either ground or the positive

supply rail, depending on the biasing, and, also, the output

cannot disengage during this half cycle. During the other

half cycle, however, the amplifier achieves a half−wave that

can have a peak equal to the total supply voltage. The

photographs in Figure 11 show the effect of the different

biasing schemes, as well as the wide bandwidth (it works

over the full audio range), that the NE5230 can achieve in

this configuration.

Half−Wave Rectifier With Positive−Going Output Swings

10W

10W

VIN

2

−

VCC

7

3+

4

6

5

VCC

VOUT

O

t

Figure 9. Rail−to−Ground Output Swing Referenced to Ground

VCC

VCC

10W

VIN

3

+7

6

2−

5

4

VOUT

VCC

10W

t

Figure 10. Negative−Going Output Referenced to VCC

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