REV. B

OP200

–10–

Dual Precision Voltage Reference

A dual OP200 and a REF43, a 2.5 V reference, can be used to

build a

± 2.5 V precision voltage reference. Maximum output

current from each reference is

±10 mA with load regulation

under 25

µV/mA. Line regulation is better than 15 µV/V and

output voltage drift is under 20

µV/°C. Output voltage noise

from 0.1 Hz to 10 Hz is typically 75

µV p-p. R1 and D1 ensure

correct start-up.

Programmable High Resolution Window Comparator

The programmable window comparator shown in Figure 9 is

easily capable of 12-bit accuracy over the full military tempera-

ture range. A dual CMOS 12-bit DAC, the DAC8212, is used

in the voltage switching mode to set the upper and lower thresh-

olds (DAC A and DAC B, respectively).

OUTB

AGND

15V

DAC A/DAC B

CS

WR

DAC

CONTROL

SIGNALS

10V

REFERENCE

1/2

OP200AZ

1/2

OP200AZ

4

4

5

7

8

18

19

20

21

24

22

2

2

3

+

–

DAC DATA BUS

PINS 6(MSB) – 17(LSB)

5

1

DGND

+

–

DAC A

DAC B

1/2

DAC8212AV

1/2

DAC8212AV

1

–15V

R3

10k

R4

10k

5V

TTL OUT

D1

1N4148

D2

1N4148

R1

10k

R2

10k

Q1

2N2222

Figure 9. Programmable High Resolution Window Comparator

1/2

OP200AZ

1/2

OP200AZ

R2

10k

–5V

7

6

5

4

2

3

8

R4

5k

–2.5V

–2.5V

6

R3

10k

R1

22k

+5V

REF43A

4

2

D1

1N914

Figure 8. Dual Precision Voltage Reference