Data Sheet

ADR3512

Rev. E | Page 15 of 16

SAMPLE APPLICATIONS

Negative Reference

Figure 39 shows how to connect the ADR3512 and a standard

CMOS operational amplifier, such as the AD8663, to provide a

negative reference voltage. This configuration provides two main

advantages: first, it requires only two devices and, therefore, does

not require excessive board space. Second, it does not require any

external resistors, meaning that the performance of this circuit

does not rely on choosing expensive devices with low temperature

coefficients to ensure accuracy.

VDD

–1.2V

AD8663

0.1µF

0.1µF

1µF

0.1µF

–VDD

ENABLE

GND FORCE

GND SENSE

8

1

6

7

2

3

ADR3512

Figure 39. Negative Reference

the reference sit at virtual ground. The negative reference voltage

and load current are taken directly from the output of the

operational amplifier. Note that, in applications where the negative

supply voltage is close to the reference output voltage, a dual-

supply, low offset, rail-to-rail output amplifier must be used to

ensure an accurate output voltage. The operational amplifier must

also be able to source or sink an appropriate amount of current

for the application.

Bipolar Output Reference

Figure 40 shows a bipolar reference configuration. By connecting

the output of the ADR3512 to the inverting terminal of an

operational amplifier, it is possible to obtain both positive and

negative reference voltages. Match Resistors R1 and R2 as close as

possible to ensure minimal difference between the negative and

positive outputs. Use resistors with low temperature coefficients

if the circuit is used in environments with large temperature swings;

otherwise, a voltage difference develops between the two outputs as

the ambient temperature changes.

+15V

–15V

–1.2V

+1.2V

ADA4000-1

0.1µF

1µF

0.1µF

R1

10kΩ

R2

10kΩ

R3

5kΩ

ADR3512

ENABLE

GND FORCE

GND SENSE

8

1

6

7

2

3

Figure 40. Bipolar Output Reference

Boosted Output Current Reference

Figure 41 shows a configuration for obtaining higher current

drive capability from the ADR3512 reference without sacrificing

accuracy. The operational amplifier regulates the current flow

than from the reference itself, allowing increased current

drive capability.

0.1µF

0.1µF

2N7002

AD8663

U6

+16V

0.1µF

1µF

R1

100Ω

200Ω

8

1

6

7

2

3

ADR3512

ENABLE

GND FORCE

GND SENSE

Figure 41. Boosted Output Current Reference

Because the current sourcing capability of this circuit depends only

adjusted to the application simply by choosing an appropriate

load device to maintain maximum output voltage accuracy.