9

Error-Amplifier in Regulated Power Supplies

The CA3160 is an ideal choice for error-amplifier service in

regulated power supplies since it can function as an error-

amplifier when the regulated output voltage is required to

approach zero.

The circuit shown in Figure 6 uses a CA3160 as an error

amplifier in a continuously adjustable 1A power supply. One

of the key features of this circuit is its ability to regulate down

to the vicinity of 0V with only one DC power supply input.

An RC network, connected between the base of the output

drive transistor and the input voltage, prevents “turn-on

overshoot”, a condition typical of many operational amplifier

regulator circuits. As the amplifier becomes operational,

this RC network ceases to have any influence on the

regulator performance.

Precision Voltage-Controlled Oscillator

The circuit diagram of a precision voltage-controlled oscillator is

shown in Figure 7. The oscillator operates with a tracking error

in the order of 0.02% and a temperature coefficient of

rail, the output pulse amplitude (V) is essentially equal to V+.

Voltmeter With High Input Resistance

The voltmeter circuit shown in Figure 8 illustrates an

application in which a number of the CA3160 characteristics

and output circuitry to permit selection of the proper output

voltage for feedback to Terminal 2 via 10k

Ω current-limiting

resistor. The circuit is powered by a single 8.4V mercury

battery. With zero input signal, the circuit consumes

somewhat less than 500

µA plus the meter current required

to indicate a given voltage. Thus, at full scale input, the total

supply current rises to slightly more than 1500

µA.

Function Generator

A function generator having a wide tuning range is shown in

Figure 9. The adjustment range, in excess of 1,000,000/1, is

accomplished by a single potentiometer. Three operational

amplifiers are utilized: a CA3160 as a voltage follower, a

CA3080 as a high speed comparator, and a second

CA3080A as a programmable current source. Three variable

constant (+10%) amplitude up to 1MHz.

CA3085

1

2

6

3

0.001

µF

4

7

6

13

8

1

5

12

CD4007A

“SWITCHES”

10

3

14

11

2

9

4

7

806K

1%

402K

1%

200K

1%

806K

1%

6

13

8

1

12

CD4007A

“SWITCHES”

10

3

100K

1%

(2)

806K

6

13

8

12

CD4007A

“SWITCHES”

10

3

806K

1%

806K

1%

1%

(4)

806K

1%

(8)

806K

1%

1

5

806K

1%

750K

1%

10V LOGIC INPUTS

PARALLELED

RESISTORS

+10.010V

LSB

MSB

98

7

6

5

4

32

1

8

+10.010V

22.1K

1%

1K

3.83K

1%

2

µF

25V

+

-

+15V

62

VOLTAGE

REGULATOR

REGULATED

VOLTAGE

ADJUST

CA3160

3

4

2

0.1

µF

+

-

1

5

6

2K

+15V

100K

VOLTAGE

FOLLOWER

7

OFFSET

NULL

OUTPUT

LOAD

10K

BIT

REQUIRED

RATIO-MATCH

1

Standard

2

±0.1%

3

±0.2%

4

±0.4%

5

±0.8%

6 - 9

±1% ABS.

FIGURE 5. 9-BIT DAC USING CMOS DIGITAL SWITCHES AND CA3160

806K

1%

5

CA3160