ADR01/ADR02/ADR03/ADR06

Rev. F | Page 16 of 20

125

25

50

75

100

0.40

0.80

0.75

0.70

0.65

0.60

0.55

0.50

0.45

–25

0

–50

SAMPLE SIZE = 5

TEMPERATURE (

∆V

1.96mV/

Figure 37. Voltage at TEMP Pin vs. Temperature

The TEMP function is provided as a convenience rather than a

precise feature. Because the voltage at the TEMP node is

acquired from the band gap core, current pulling from this pin

TEMP output with a suitable low bias current op amp, such as

the AD8601, AD820, or OP1177, all of which would result in

buffering, even tens of microamps drawn from the TEMP pin

U2

15V

U1

ADR01/

ADR02/

ADR03/

ADR06

TEMP TRIM

GND

V–

V+

OP1177

1.9mV/

Figure 38. Temperature Monitoring

NEGATIVE REFERENCE

Without using any matching resistors, a negative reference can

be configured as shown in Figure 39. For the ADR01, the volt-

at virtual ground, U2 closes the loop by forcing the GND pin to

be the negative reference node. U2 should be a precision op

amp with a low offset voltage characteristic.

U2

+15V

–15V

V–

V+

OP1177

U1

ADR01/

ADR02/

ADR03/

ADR06

TEMP TRIM

GND

5V TO 15V

Figure 39. Negative Reference

LOW COST CURRENT SOURCE

Unlike most references, the ADR01/ADR02/ADR03/ADR06

employ an NPN Darlington in which the quiescent current

remains constant with respect to the load current, as shown in

Figure 24. As a result, a current source can be configured as

0.55 to 0.65 mA, limiting this circuit to general-purpose

applications.

ADR01/

ADR02/

ADR03/

ADR06

GND

Figure 40. Low Cost Current Source

PRECISION CURRENT SOURCE WITH

ADJUSTABLE OUTPUT

A precision current source, on the other hand, can be

implemented with the circuit shown in Figure 41. By adding a

mechanical or digital potentiometer, this circuit becomes an

adjustable current source. If a digital potentiometer is used, the

load current is simply the voltage across terminals B to W of the

SET

REF

L

R

D

V

I

×

=

(1)

where D is the decimal equivalent of the digital potentiometer

input code.

U2

+12V

–12V

W

B

A

U1

ADR01/

ADR02/

ADR03/

ADR06

TEMP TRIM

GND

V–

V+

OP1177

AD5201

+12V

1k

Ω

1k

Ω

100k

Ω

Figure 41. Programmable 0 to 5 mA Current Source