SA5230FE_技术文档

INTEGRATED CIRCUITS

NE/SA5230

Low voltage operational amplifier

Product specification

1994 Aug 31

Philips

Semiconductors

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

DESCRIPTION

PIN CONFIGURATION

The NE5230 is a very low voltage operational amplifier that can

perform with a voltage supply as low as 1.8V or as high as 15V. In

addition, split or single supplies can be used, and the output will

swing to ground when applying the latter. There is a bias adjusting

pin which controls the supply current required by the device and

thereby controls its power consumption. If the part is operated at

±0.9V supply voltages, the current required is only 110µA when the

current control pin is left open. Even with this low power

consumption, the device obtains a typical unity gain bandwidth of

180kHz. When the bias adjusting pin is connected to the negative

supply, the unity gain bandwidth is typically 600kHz while the supply

current is increased to 600µA. In this mode, the part will supply full

power output beyond the audio range.

N, D, FE Packages

1

2

3

4

8

7

6

5

NC

–IN

+IN

V

CC

–

+

OUTPUT

V

EE

BIAS ADJ.

SP00250

Figure 1. Pin Configuration

The NE5230 also has a unique input stage that allows the

common-mode input range to go above the positive and below the

negative supply voltages by 250mV. This provides for the largest

possible input voltages for low voltage applications. The part is also

internally-compensated to reduce external component count.

APPLICATIONS

• Portable precision instruments

• Remote transducer amplifier

• Portable audio equipment

The NE5230 has a low input bias current of typically ±40nA, and a

large open-loop gain of 125dB. These two specifications are

beneficial when using the device in transducer applications. The

large open-loop gain gives very accurate signal processing because

of the large “excess” loop gain in a closed-loop system.

• Rail-to-rail comparators

• Half-wave rectification without diodes

The output stage is a class AB type that can swing to within 100mV

of the supply voltages for the largest dynamic range that is needed

in many applications. The NE5230 is ideal for portable audio

equipment and remote transducers because of its low power

consumption, unity gain bandwidth, and 30nV/√Hz noise

specification.

• Remote temperature transducer with 4 to 20mA output

transmission

FEATURES

• Works down to 1.8V supply voltages

• Adjustable supply current

• Low noise

• Common-mode includes both rails

• V

within 100mV of both rails

OUT

ORDERING INFORMATION

DESCRIPTION

TEMPERATURE RANGE

0 to +70°C

ORDER CODE

NE5230D

DWG #

SOT96-1

SOT97-1

SOT96-1

0580A

8-Pin Plastic Small Outline (SO) Package

8-Pin Plastic Dual In-Line Package (DIP)

8-Pin Plastic Small Outline (SO) Package

8-Pin Ceramic Dual In-Line Package (CERDIP)

8-Pin Plastic Dual In-Line Package (DIP)

0 to +70°C

NE5230N

-40°C to +85°C

SA5230D

SA5230FE

SA5230N

SOT97-1

2

1994 Aug 31

853-0942 13721

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

ABSOLUTE MAXIMUM RATINGS

SYMBOL

PARAMETER

RATING

18

UNIT

V

Single supply voltage

Dual supply voltage

CC

±9

V

S

1

Input voltage

±9 (18)

V

IN

1

Differential input voltage

±V

S

V

P

Common-mode voltage (positive)

Common-mode voltage (negative)

V

+0.5

V

CM

D

CC

V

-0.5

V

EE

2

Power dissipation

500

150

mW

°C

s

2

T

J

Operating junction temperature

2, 3

80Output short-circuit duration to either power supply pin

Storage temperature

Indefinite

-65 to 150

300

T

°C

STG

Lead soldering temperature (10sec max)

SOLD

NOTES:

1. Can exceed the supply voltages when V ≤ ±7.5V (15V).

S

2. The maximum operating junction temperature is 150°C. At elevated temperatures, devices must be derated according to the package ther-

mal resistance and device mounting conditions. Derate above 25°C at the following rates:

FE package at 6.7mW/°C

N package at 9.5mW/°C

D package at 6.25mW/°C

3. Momentary shorts to either supply are permitted in accordance to transient thermal impedance limitations determined by the package and

device mounting conditions.

RECOMMENDED OPERATING CONDITIONS

PARAMETER

RATING

1.8 to 15

UNIT

Single supply voltage

V

Dual supply voltage

±0.9 to ±7.5

Common-mode voltage (positive)

Common-mode voltage (negative)

V

CC

+0.25

V

EE

-0.25

Temperature

NE grade

SA grade

0 to 70

-40 to 85

°C

3

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

DC AND AC ELECTRICAL CHARACTERISTICS

Unless otherwise specified, ±0.9V ≤ V ≤ +7.5V or equivalent single supply, R =10kΩ, full input common-mode range, over full operating

S

L

temperature range.

NE/SA5230

SYMBOL

PARAMETER

TEST CONDITIONS

BIAS

UNIT

Min

Typ

0.4

3

Max

3

T =25°C

A

Any

V

Offset voltage

mV

OS

T =25°C

A

4

Drift

Any

2

5

µV/°C

OS

T =25°C

High

Low

High

Low

High

Low

High

Low

High

Low

High

Low

High

Low

High

Low

High

Low

High

Any

3

50

A

T =25°C

A

3

30

I

Offset current

nA

nA/°C

nA

OS

100

60

0.5

0.3

40

1.4

150

60

Drift

OS

B

T =25°C

A

T =25°C

A

20

Bias current

Drift

200

150

4

2

nA/°C

µA

B

2

4

T =25°C

110

600

160

750

250

800

550

1.6

600

1.7

A

T =25°C

A

V =±0.9V

S

I

S

Supply current

T =25°C

320

1.1

A

T =25°C

A

V =±7.5V

S

µA

–

+

V

≤6mV, T =25°C

V -0.25

V +0.25

OS

A

V

Common-mode input range

Common-mode rejection ratio

V

CM

–

+

Any

V

R =10kΩ, V =±7.5V,

S

CM

Any

85

95

T =25°C

A

CMRR

PSRR

V =±7.5V

dB

S

R =10kΩ, V =±7.5V

Any

High

Low

High

Low

Any

80

90

85

75

80

4

S

CM

T =25°C

A

105

95

T =25°C

A

Power supply rejection ratio

dB

source

V =±7.5V

S

10

15

5

sink

source

sink

V =±7.5V

S

Any

5

V =±7.5V

S

Any

1

V =±7.5V

S

Any

2

6

I

L

Load current

mA

source

sink

V =±0.9V, T =25°C

High

Low

High

Low

4

6

S

A

V =±0.9V, T =25°C

5

7

S

A

source

sink

V =±7.5V, T =25°C

16

32

2000

750

S

A

V =±7.5V, T =25°C

S

A

R =10kΩ, T =25°C

120

60

V/mV

L

A

R =10kΩ, T =25°C

L

A

VOL

Large-signal open-loop gain

V =±7.5V

S

100

50

4

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

DC AND AC ELECTRICAL CHARACTERISTICS (Continued)

NE/SA5230

SYMBOL

PARAMETER

Output voltage swing

Slew rate

TEST CONDITIONS

T =25°C +SW

BIAS

UNIT

Min

750

Typ

800

Max

Any

High

Low

High

Low

Any

High

Low

High

Low

A

T =25°C -SW

750

A

V =±0.9V

mV

S

+SW

-SW

700

V

OUT

T =25°C +SW

A

7.30

-7.32

7.25

-7.30

7.35

-7.35

7.30

-7.35

0.25

0.09

0.6

V =±7.5V

T =25°C -SW

A

S

V

+SW

-SW

T =25°C

A

SR

V/µs

T =25°C

A

C =100pF, T =25°C

L

A

BW

Inverting unity gain bandwidth

Phase margin

MHz

Deg.

µs

C =100pF, T =25°C

0.25

70

L

A

θ

C =100pF, T =25°C

L A

M

C =100pF, 0.1%

L

2

t

S

Settling time

C =100pF, 0.1%

L

5

R =0Ω, f=1kHz

S

30

V

INN

Input noise

nV/√Hz

R =0Ω, f=1kHz

S

60

V =±7.5V

S

High

0.003

0.002

A =1, V =500mV, f=1kHz

V

IN

THD

Total Harmonic Distortion

%

V =±0.9V

S

A =1, V =500mV, f=1kHz

V

IN

5

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

The input stage was designed to overcome two important problems

for rail-to-rail capability. As the common-mode voltage moves from

the range where only the NPN pair was operating to where both of

the input pairs were operating, the effective transconductance would

change by a factor of two. Frequency compensation for the ranges

where one input pair was operating would, of course, not be optimal

for the range where both pairs were operating. Secondly, fast

changes in the common-mode voltage would abruptly saturate and

restore the emitter current sources, causing transient distortion.

These problems were overcome by assuring that only the input

transistor pair which is able to function properly is active. The NPN

THEORY OF OPERATION

Input Stage

Operational amplifiers which are able to function at minimum supply

voltages should have input and output stage swings capable of

reaching both supply voltages within a few millivolts in order to

achieve ease of quiescent biasing and to have maximum

input/output signal handling capability. The input stage of the

NE5230 has a common-mode voltage range that not only includes

the entire supply voltage range, but also allows either supply to be

exceeded by 250mV without increasing the input offset voltage by

more than 6mV. This is unequalled by any other operational

amplifier today.

pair is normally activated by the current source I through Q5 and

B1

the current mirror Q6 and Q7, assuming the PNP pair is

non-conducting. When the common-mode input voltage passes

In order to accomplish the feat of rail-to-rail input common-mode

range, two emitter-coupled differential pairs are placed in parallel so

that the common-mode voltage of one can reach the positive supply

rail and the other can reach the negative supply rail. The simplified

schematic of Figure 2 shows how the complementary

below the reference voltage, V =0.8V at the base of Q5, the

B1

emitter current is gradually steered toward the PNP pair, away from

the NPN pair. The transfer of the emitter currents between the

complementary input pairs occurs in a voltage range of about

120mV around the reference voltage V . In this way the sum of the

B1

emitter-coupler transistors are configured to form the basic input

stage cell. Common-mode input signal voltages in the range from

emitter currents for each of the NPN and PNP transistor pairs is kept

constant; this ensures that the transconductance of the parallel

combination will be constant, since the transconductance of bipolar

transistors is proportional to their emitter currents.

0.8V above V to V are handled completely by the NPN pair, Q3

EE

CC

and Q4, while common-mode input signal voltages in the range of

to 0.8V above V are processed only by the PNP pair, Q1 and

V

EE

An essential requirement of this kind of input stage is to minimize

the changes in input offset voltage between that of the NPN and

PNP transistor pair which occurs when the input common-mode

Q2. The intermediate range of input voltages requires that both the

NPN and PNP pairs are operating. The collector currents of the

input transistors are summed by the current combiner circuit

composed of transistors Q8 through Q11 into one output current.

Transistor Q8 is connected as a diode to ensure that the outputs of

Q2 and Q4 are properly subtracted from those of Q1 and Q3.

voltage crosses the internal reference voltage, V . Careful circuit

B1

layout with a cross-coupled quad for each input pair has yielded a

typical input offset voltage of less than 0.3mV and a change in the

input offset voltage of less than 0.1mV.

V

CC

R11

R10

+

V

b2

V

Q11

Q10

I

b1

Q4

Q3

Q2

Q1

V

IN+

IN–

I

OUT

Q9

Q8

Q5

+

V

Q7

b1

Q6

R8

R9

V

EE

SL00251

Figure 2. Input Stage

6

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

diodes D1 and D2 are proportional to the logarithm of the square of

Output Stage

the reference current I . When the diode characteristics and

B1

Processing output voltage swings that nominally reach to less than

100mV of either supply voltage can only be achieved by a pair of

complementary common-emitter connected transistors. Normally,

such a configuration causes complex feed-forward signal paths that

develop by combining biasing and driving which can be found in

previous low supply voltage designs. The unique output stage of the

NE5230 separates the functions of driving and biasing, as shown in

the simplified schematic of Figure 3, and has the advantage of a

shorter signal path which leads to increasing the effective

bandwidth.

temperatures of the pairs Q1, D1 and Q3, Q2 are equal, the relation

I ×I =I ×I is satisfied.

OP ON B1 B1

Separating the functions of biasing and driving prevents the driving

signals from becoming delayed by the biasing circuit. The output

Darlington transistors are directly accessible for in-phase driving

signals on the bases of Q5 and Q2. This is very important for simple

high-frequency compensation. The output transistors can be

high-frequency compensated by Miller capacitors CM1A and CM1B

connected from the collectors to the bases of the output Darlington

transistors.

This output stage consists of two parts: the Darlington output

transistors and the class AB control regulator. The output transistor

Q3 connected with the Darlington transistors Q4 and Q5 can source

up to 10mA to an output load. The output of NPN Darlington

connected transistors Q1 and Q2 together are able to sink an output

current of 10mA. Accurate and efficient class AB control is

necessary to insure that none of the output transistors are ever

completely cut off. This is accomplished by the differential amplifier

(formed by Q8 and Q9) which controls the biasing of the output

transistors. The differential amplifier compares the summed voltages

across two diodes, D1 and D2, at the base of Q8 with the summed

voltages across the base-emitter diodes of the output transistors Q1

and Q3. The base-emitter voltage of Q3 is converted into a current

by Q6 and R6 and reconverted into a voltage across the

A general-purpose op amp of this type must have enough open-loop

gain for applications when the output is driving a low resistance

load. The NE5230 accomplishes this by inserting an intermediate

common-emitter stage between the input and output stages. The

three stages provide a very large gain, but the op amp now has

three natural dominant poles — one at the output of each

common-emitter stage. Frequency compensation is implemented

with a simple scheme of nested, pole-splitting Miller integrators. The

Miller capacitors CM1A and CM1B are the first part of the nested

structure, and provide compensation for the output and intermediate

stages. A second pair of Miller integrators provide pole-splitting

compensation for the pole from the input stage and the pole

resulting from the compensated combination of poles from the

intermediate and output stages. The result is a stable,

base-emitter diode of Q7 and R7. The summed voltage across the

base-emitter diodes of the output transistors Q3 and Q1 is

proportional to the logarithm of the product of the push and pull

internally-compensated op amp with a phase margin of 70 degrees.

currents I and I , respectively. The combined voltages across

OP

ON

V

CC

R6

I

b3

b1

b2

Q3

Q6

Q5

V

b5

I

OP

Q4

CM1B

CM1A

V

OUT

Q2

V

b2

I

ON

Q8

Q9

R7

D1

Q7

Q1

I

b4

I

b5

D2

V

EE

SL00252

Figure 3. Output Stage

7

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

triangular waveforms. The gain-bandwidth can be varied from

between 250kHz at low bias to 600kHz at high bias current. The

slew rate range is 0.08V/µs at low bias and 0.25V/µs at high bias.

THERMAL CONSIDERATIONS

When using the NE5230, the internal power dissipation capabilities

of each package should be considered. Philips Semiconductors

does not recommend operation at die temperatures above 110°C in

the SO package because of its inherently smaller package mass.

Die temperatures of 150°C can be tolerated in all the other

packages. With this in mind, the following equation can be used to

estimate the die temperature:

800

700

600

500

T = T + (P × θ

)

(1)

J

A

D

JA

400

300

Where

T_A5 AmbientTemperature

T_J+ Die Temperature

P_D5 Power Dissipation

200

+ (I_CCx V_CC

)

q_JA5 Packagethermalresistance

100

+ 270^oCńW for SO * 8 in PC

500

600700

200

300

400

board mounting

UNITY GAIN BANDWIDTH (kHz)

See the packaging section for information regarding other methods

of mounting.

a. Unity Gain Bandwidth vs Power Supply Current for

V

CC

= ±0.9V

θ

=100°C/W for the plastic DIP;

=110°C/W for the ceramic DIP.

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

JA

V

= 15V

T

= 25°C

CC

A

V

= 12V

= 9V

The maximum supply voltage for the part is 15V and the typical

supply current is 1.1mA (1.6mA max). For operation at supply

voltages other than the maximum, see the data sheet for I versus

V

= 6V

= 3V

CC

V

curves. The supply current is somewhat proportional to

CC

V

= 2V

temperature and varies no more than 100µA between 25°C and

either temperature extreme.

CC

= 1.8V

Operation at higher junction temperatures than that recommended is

possible but will result in lower MTBF (Mean Time Between

Failures). This should be considered before operating beyond

recommended die temperature because of the overall reliability

degradation.

0

1

2

3

4

5

10

(Ω)

10

R

ADJ

b. I Current vs Bias Current Adjusting Resistor for

CC

Several Supply Voltages

SL00253

DESIGN TECHNIQUES AND APPLICATIONS

The NE5230 is a very user-friendly amplifier for an engineer to

design into any type of system. The supply current adjust pin (Pin 5)

can be left open or tied through a pot or fixed resistor to the most

negative supply (i.e., ground for single supply or to the negative

supply for split supplies). The minimum supply current is achieved

by leaving this pin open. In this state it will also decrease the

bandwidth and slew rate. When tied directly to the most negative

Figure 4.

The full output power bandwidth range for V equals 2V, is above

40kHz for the maximum bias current setting and greater than 10kHz

at the minimum bias current setting.

CC

If extremely low signal distortion (<0.05%) is required at low supply

voltages, exclude the common-mode crossover point (V ) from the

common-mode signal range. This can be accomplished by proper

bias selection or by using an inverting amplifier configuration.

B1

supply, the device has full bandwidth, slew rate and I . The

CC

programming of the current-control pin depends on the trade-offs

which can be made in the designer’s application. The graph in

Most single supply designs necessitate that the inputs to the op amp

Figure 4 will help by showing bandwidth versus I . As can be seen,

CC

be biased between V and ground. This is to assure that the input

the supply current can be varied anywhere over the range of 100µA

to 600µA for a supply voltage of 1.8V. An external resistor can be

inserted between the current control pin and the most negative

supply. The resistor can be selected between 1Ω to 100kΩ to

provide any required supply current over the indicated range. In

addition, a small varying voltage on the bias current control pin could

be used for such exotic things as changing the gain-bandwidth for

voltage controlled low pass filters or amplitude modulation.

Furthermore, control over the slew rate and the rise time of the

amplifier can be obtained in the same manner. This control over the

slew rate also changes the settling time and overshoot in pulse

response applications. The settling time to 0.1% changes from 5µs

at low bias to 2µs at high bias. The supply current control can also

be utilized for wave-shaping applications such as for pulse or

CC

signal swing is within the working common-mode range of the

amplifier. This leads to another helpful and unique property of the

NE5230 that other CMOS and bipolar low voltage parts cannot

achieve. It is the simple fact that the input common-mode voltage

can go beyond either the positive or negative supply voltages. This

benefit is made very clear in a non-inverting voltage-follower

configuration. This is shown in Figure 5 where the input sine wave

allows an undistorted output sine wave which will swing less than

100mV of either supply voltage. Many competitive parts will show

severe clipping caused by input common-mode limitations. The

NE5230 in this configuration offers more freedom for quiescent

biasing of the inputs close to the positive supply rail where similar op

amps would not allow signal processing.

8

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

when no current is flowing, but also can power the transducer at the

remote location. Usually the transducer itself is not equipped to

provide for the current transmission. The unique features of the

NE5230 can provide high output current capability coupled with low

power consumption. It can be remotely connected to the transducer

to create a current loop with minimal external components. The

circuit for this is shown in Figure 6. Here, the part is configured as a

voltage-to-current, or transconductance amplifier. This is a novel

circuit that takes advantage of the NE5230’s large open-loop gain.

In AC applications, the load current will decrease as the open-loop

gain rolls off in magnitude. The low offset voltage and current

sinking capabilities of the NE5230 must also be considered in this

application.

V+

+

–

V–

V+

V

I

CC

OUT

3

2

+

–

REMOTE

POWER

SUPPLY

7

+

–

V

NE5230

6

NE5230

5

4

V

EE

T

R

A

N

S

D

U

C

E

R

V–

V+

R

L

V

IN

R

C

OTHER

PARTS

NOTES:

1. I

= V

OUT

IN/RC

V

V–

* 1.8V * V

For R = 1Ω

SL00254

C

REMOTE

INMAX

2. R

≈

L MAX

I

V

I

OUT

IN

OUT

Figure 5. In a Non-Inverting Voltage-Follower Configuration,

the NE5230 will Give Full Rail-to-Rail Swing. Other Low Voltage

Amplifiers will not Because they are Limited by their Input

Common-Mode Range and Output Swing Capability.

4mA

4mV

20mA

20mV

a. The NE5230 as a Remote Transducer Transconductance

Amp With 4-20mA Current Transmission Output Capability

There are not as many considerations when designing with the

NE5230 as with other devices. Since the NE5230 is

+

internally-compensated and has a unity gain-bandwidth of 600kHz,

board layout is not so stringent as for very high frequency devices

such as the NE5205. The output capability of the NE5230 allows it

to drive relatively high capacitive loads and small resistive loads.

The power supply pins should be decoupled with a low-pass RC

network as close to the supply pins as possible to eliminate 60Hz

and other external power line noise, although the power supply

rejection ratio (PSRR) for the part is very high. The pinout for the

NE5230 is the same as the standard single op amp pinout with the

exception of the bias current adjusting pin.

R

C

V

IN

V

CC

–

3

2

+

–

7

+

–

V

CC

6

NE5230

5

4

V

EE

+ I

OUT

R

L

REMOTE TRANSDUCER WITH CURRENT

TRANSMISSION

b. The Same Type of Circuit as Figure 5a, but for Sourcing

Current to the Load

There are many ways to transmit information along two wires, but

current transmission is the most beneficial when the sensing of

remote signals is the aim. It is further enhanced in the form of 4 to

20mA information which is used in many control-type systems. This

method of transmission provides immunity from line voltage drops,

large load resistance variations, and voltage noise pickup. The zero

reference of 4mA not only can show if there is a break in the line

SL00255

Figure 6.

9

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

The NE5230 circuit shown in Figure 6 is a pseudo transistor

configuration. The inverting input is equivalent to the “base,” the

long line is used which causes high line resistance, a current

repeater could be inserted into the line. The same configuration of

Figure 6 can be used with exception of a resistor across the input

and line ground to convert the current back to voltage. Again, the

current sensing resistor will set up the transconductance and the

part will receive power from the line.

point where V and the non-inverting input meet is the “emitter,”

EE

and the connection after the output diode meets the V pin is the

CC

collector. The output diode is essential to keep the output from

saturating in this configuration. From here it can be seen that the

base and emitter form a voltage-follower and the voltage present at

R

must equal the input voltage present at the inverting input. Also,

C

the emitter and collector form a current-follower and the current

flowing through R is equivalent to the current through R and the

amplifier. This sets up the current loop. Therefore, the following

equation can be formulated for the working current transmission line.

The load current is:

TEMPERATURE TRANSDUCER

C

L

A variation on the previous circuit makes use of the supply current

control pin. The voltage present at this pin is proportional to absolute

temperature (PTAT) because it is produced by the amplifier bias

current through an internal resistor divider in a PTAT cell. If the

control pin is connected to the input pin, the NE5230 itself can be

used as a temperature transducer. If the center tap of a resistive pot

is connected to the control pin with one side to ground and the other

to the inverting input, the voltage can be changed to give different

temperature versus output current conditions (see Figure 7). For

additional control, the output current is still proportional to the input

voltage differential divided by the current sense resistor.

I =V /R

C

(2)

L

IN

and proportional to the input voltage for a set R . Also, the current is

C

constant no matter what load resistance is used while within the

operating bandwidth range of the op amp. When the NE5230’s

supply voltage falls past a certain point, the current cannot remain

constant. This is the “voltage compliance” and is very good for this

application because of the near rail output voltage. The equation

that determines the voltage compliance as well as the largest

possible load resistor for the NE5230 is as follows:

When using the NE5230 as a temperature transducer, the thermal

considerations in the previous section must be kept in mind.

R

=[V

)-V

- V

]/I

L

(3)

L max

remote supply

CC min

IN max

Where V

is the worst-case power supply voltage

CC min

V

I

CC

5

OUT

(approximately 1.8V) that will still keep the part operational. As an

example, when using a 15V remote power supply, a current sensing

resistor of 1Ω, and an input voltage (V ) of 20mV, the output current

3

2

+

–

REMOTE

POWER

SUPPLY

7

+

V

6

IN

NE5230

(I ) is 20mA. Furthermore, a load resistance of zero to

L

approximately 650Ω can be inserted in the loop without any change

in current when the bias current-control pin is tied to the negative

supply pin. The voltage drop across the load and line resistance will

not affect the NE5230 because it will operate down to 1.8V. With a

15V remote supply, the voltage available at the amplifier is still

enough to power it with the maximum 20mA output into the 650Ω

load.

–

4

V

EE

10

R

L

200

R

C

What this means is that several instruments, such as a chart

recorder, a meter, or a controller, as well as a long cable, can be

connected in series on the loop and still obtain accurate readings if

the total resistance does not exceed 650Ω. Furthermore, any

variation of resistance in this range will not change the output

current.

NOTES:

1. I

= V

OUT

IN/RC

V

* 1.8V * V

REMOTE

INMAX

2. R

≈

L MAX

For R = 1Ω

C

I

Any voltage output type transducer can be used, but one that does

not need external DC voltage or current excitation to limit the

maximum possible load resistance is preferable. Even this problem

can be surmounted if the supply power needed by the transducer is

compatible with the NE5230. The power goes up the line to the

transducer and amplifier while the transducer signal is sent back via

the current output of the NE5230 transconductance configuration.

OUT

I

V

OUT

IN

4mA

4mV

20mA

20mV

SL00256

Figure 7. NE5230 Remote Temperature Transducer Utilizing

4-20mA Current Transmission. This Application Shows the use

of the Accessibility of the PTAT Cell in the Device to Make the

Part, Itself, a Transducer

The voltage range on the input can be changed for transducers that

produce a large output by simply increasing the current sense

resistor to get the corresponding 4 to 20mA output current. If a very

10

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

because the waveform forces the amplifier to swing the output

HALF-WAVE RECTIFIER WITH RAIL-TO-GROUND

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 9 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.

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. This can be seen in Figure 8. Circuit (a) is

biased to ground, while circuit (b) 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.

By adding another NE5230 in an inverting summer configuration at

the output of the half-wave rectifier, a full-wave can be realized. The

values for the input and feedback resistors must be chosen so that

each peak will have equal amplitudes. A table for calculating values

is included in Figure 10. The summing network combines the input

signal at the half-wave and adds it to double the half-wave’s output,

resulting in the full-wave. The output waveform can be referenced to

the supply or ground, depending on the half-wave configuration.

Again, no diodes are needed to achieve the rectification.

This circuit could be used in conjunction with the remote transducer

to convert a received AC output signal into a DC level at the

full-wave output for meters or chart recorders that need DC levels.

It can be seen in these configurations that the op amp cannot

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

10

V

CC

10

2

V

IN

7

–

+

6

V

OUT

V

5

CC

3

4

O

t

a. Rail-to-Ground Output Swing Referenced to Ground

V

CC

3

7

+

6

V

OUT

10

5

2

–

4

V

CC

IN

10

V

CC

t

b. Negative-Going Output Referenced to V

CC

SL00257

Figure 8. Half-Wave Rectifier With Positive-Going Output Swings

11

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

500mV/Div 200µS/Div

Biased to Ground

500mV/Div 20µS/Div

Biased to Ground

500mV/Div 20µS/Div

Biased to Positive Rail

SL00258

Figure 9. Performance Waveforms for the Circuits in Figure 8.

Good Response is Shown at 1and 10kHz for Both Circuits Under Full Swing With a 2V Supply

12

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

500mV

520µs

INPUT

HALF-WAVE

OUTPUT

FULL-WAVE

OUTPUT

+V

IN

a

500mV

b

–V

IN

R3

R5

3

+

V

CC

7

R4

6

2

A

+V

–V

1

–

+

IN

5

a

b

R1

a

6

2

4

+V

–

A

B

2

FULL-WAVE

5

b

3

V

4

EE

IN

R2

+V

V

B

EE

0

2a

NOTES:

R2 = 2 R1

–2V

IN

HALF-WAVE

R4 = R5 = R3

+V will vary output reference.

B

For single supply operation V

can be grounded on A2.

SL00259

EE

Figure 10. Adding an Inverting Summer to the Input and Output of the Half-Wave will Result in Full-Wave

CONCLUSION

REFERENCES

The NE5230 is a versatile op amp in its own right. The part was

designed to give low voltage and low power operation without the

limitations of previously available amplifiers that had a multitude of

problems. The previous application examples are unique to this

amplifier and save the user money by excluding various passive

components that would have been needed if not for the NE5230’s

special input and output stages.

Johan H. Huijsing, Multi-stage Amplifier with Capacitive Nesting for

Frequency Compensation, U.S. Patent Application Serial

No. 602.234, filed April 19, 1984.

Bob Blauschild, Differential Amplifier with Rail-to-Rail Capability,

U.S. Patent Application Serial No. 525.181, filed August 23, 1983.

Operational Amplifiers - Characteristics and Applications,

Robert G. Irvine, Prentice-Hall, Inc., Englewood Cliffs, NJ 07632, 1981.

The NE5230 has a combination of novel specifications which allows

the designer to implement it easily into existing low-supply voltage

designs and to enhance their performance. It also offers the

engineer the freedom to achieve greater amplifier system design

goals. The low input referenced noise voltage eases the restrictions

on designs where S/N ratios are important. The wide full-power

bandwidth and output load handling capability allow it to fit into

portable audio applications. The truly ample open-loop gain and low

power consumption easily lend themselves to the requirements of

remote transducer applications. The low, untrimmed typical offset

voltage and low offset currents help to reduce errors in signal

processing designs. The amplifier is well isolated from changes on

the supply lines by its typical power supply rejection ratio of 105dB.

Transducer Interface Handbook - A Guide to Analog Signal

Conditioning, Edited by Daniel H. Sheingold, Analog Devices, Inc.,

Norwood, MA 02062, 1981.

13

1994 Aug 31

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

SO8: plastic small outline package; 8 leads; body width 3.9mm

SOT96-1

15

August 31, 1994

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

DIP8: plastic dual in-line package; 8 leads (300 mil)

SOT97-1

16

August 31, 1994

Philips Semiconductors

Product specification

Low voltage operational amplifier

NE/SA5230

DEFINITIONS

Data Sheet Identification

Product Status

Definition

This data sheet contains the design target or goal specifications for product development. Specifications

may change in any manner without notice.

Objective Specification

Formative or in Design

This data sheet contains preliminary data, and supplementary data will be published at a later date. Philips

Semiconductors reserves the right to make changes at any time without notice in order to improve design

and supply the best possible product.

Preliminary Specification

Product Specification

Preproduction Product

Full Production

This data sheet contains Final Specifications. Philips Semiconductors reserves the right to make changes

at any time without notice, in order to improve design and supply the best possible product.

Philips Semiconductors and Philips Electronics North America Corporation reserve the right to make changes, without notice, in the products,

including circuits, standard cells, and/or software, described or contained herein in order to improve design and/or performance. Philips

Semiconductors assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright,

or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask

work right infringement, unless otherwise specified. Applications that are described herein for any of these products are for illustrative purposes

only. PhilipsSemiconductorsmakesnorepresentationorwarrantythatsuchapplicationswillbesuitableforthespecifiedusewithoutfurthertesting

or modification.

LIFE SUPPORT APPLICATIONS

Philips Semiconductors and Philips Electronics North America Corporation Products are not designed for use in life support appliances, devices,

orsystemswheremalfunctionofaPhilipsSemiconductorsandPhilipsElectronicsNorthAmericaCorporationProductcanreasonablybeexpected

to result in a personal injury. Philips Semiconductors and Philips Electronics North America Corporation customers using or selling Philips

Semiconductors and Philips Electronics North America Corporation Products for use in such applications do so at their own risk and agree to fully

indemnify Philips Semiconductors and Philips Electronics North America Corporation for any damages resulting from such improper use or sale.

Philips Semiconductors

811 East Arques Avenue

P.O. Box 3409

Sunnyvale, California 94088–3409

Philips Semiconductors and Philips Electronics North America Corporation

register eligible circuits under the Semiconductor Chip Protection Act.

Copyright Philips Electronics North America Corporation 1994

Telephone 800-234-7381

18

August 31, 1994


型号：	SA5230FE
厂家：	NXP
描述：	Low voltage operational amplifier 低电压运算放大器运算放大器放大器电路
文件：	总17页 (文件大小：193K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

SA5230FE [NXP]

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