REF02

Rev. F | Page 11 of 16

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

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

PRECISION CURRENT SOURCE

A current source with 35 V output compliance and excellent

output impedance can be obtained using this circuit. REF02

keeps the line voltage and power dissipation constant in device;

the only important error consideration at room temperature is

the negative supply rejection of the op amp. The typical 3 µV/V

PSRR of the OP02E will create a 20 ppm change (3 µV/V ×

35 V/5 V) in output current over a 25 V range. For example, a

5 mA current source can be built (R = 1 kΩ) with 350 MΩ

output impedance.

Two REF01s and one REF02 can be stacked to yield 5.000 V,

15.000 V, and 25.000 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 the noise voltage of the devices. A load bypass resistor

regulator.

GND

REF02

GND

REF02

OP02E

C

C

R

2

2

2

6

6

7

3

4

6

4

4

+50V

–5V

5V

R

35V

20

R

(TRIM FOR

CALIBRATION)

TO 25V

1

2

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

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

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

However, care must be taken to ensure that the total load

currents do not exceed the maximum usable current (typically

21 mA).

Figure 22. Precision Current Source