REF02

Rev. I | Page 11 of 16

TEMPERATURE MONITORING

The REF02 provides a TEMP output (Pin 3) that varies linearly

with temperature. This output can be used to monitor the

approximately 550 mV at 25°C, and the temperature coefficient

is approximately 1.96 mV/°C (see Figure 18).

850

800

750

700

650

600

550

500

450

400

–50

–25

0

25

50

75

100

125

TEMPERATURE (

°C)

SAMPLE SIZE = 6

J, S, AND P PACKAGES

Z PACKAGE AND 833 PRODUCT

Figure 18. Voltage at TEMP Pin vs. Temperature

A voltage change of 39.2 mV at the TEMP pin corresponds to a

20°C change in temperature.

The TEMP function is provided as a convenience rather than a

precise feature. Since the voltage at the TEMP node is acquired

from the band gap core, current pulling from this pin has a

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

the AD8601, AD820, or OP1177. Using any of these three op

Figure 19). Without buffering, even tens of microamps drawn

TEMP

TRIM

GND

U1

OP1177

V+

V–

15V

U2

1.9mV/

°C

REF02

Figure 19. Temperature Monitoring

GND

REF02

4

6

2

TEMP

3

CMP02

2

3

8

4

R6

1

7

R7

27k

Ω

R1

(9.2k

Ω)

R3

(1.3k

Ω)

R2

1.5k

Ω

R4

2.7k

Ω

R5

2.2k

Ω

V+

V–

–

+

HEATING

ELEMENT

V+ (12V TO 32V)

(SEE NOTE 1)

NOTES

1. REF02 SHOULD BE THERMALLY CONNECTED

TO SUBSTANCE BEING HEATED.

2. NUMBERS IN PARENTHESES ARE FOR A

SETPOINT TEMPERATURE OF 60

°C.

3. R3 = R1

|| R2 || R6

Figure 20. Temperature Controller

REFERENCE STACK WITH EXCELLENT LINE

REGULATION

Two REF01s and one REF02 can be stacked to yield 5.00 V,

15.00 V, and 25.00 V outputs. An additional advantage is near-

perfect line regulation of the 5.0 V and 15.0 V output. A 27 V to

55 V input change produces an output change that is less than

regulator.

In general, any number of REF01s and REF02s can be stacked

this way. For example, 10 devices yield 10 outputs in 5 V or 10 V

steps. The line voltage can change from 100 V to 130 V. Care

must be taken, however, to ensure that the total load currents

do not exceed the maximum usable current (typically 21 mA).

GND

REF02

GND

REF02

GND

REF02

TRIM

TRIM

10k

Ω

10k

Ω

6.8k

Ω

10k

Ω

2

6

5

4

2

6

5

4

2

6

5

4

15V

10V

5V

TRIM

27V TO 55V

Figure 21. Reference Stack