OP77

Data Sheet

Rev. G | Page 14 of 16

+15V

–15V

RS

1kΩ

R1

2kΩ

CC

RF

100kΩ

D1

1N4148

7

6

4

2

3

0.1µF

0.1µF

VOUT

VTH

VIN

OP77

Figure 36. Precision Threshold Detector/Amplifier

When VIN < VTH, amplifier output swings negative, reversing the

biasing diode D1. VO = VTH if RL= ∞ when VIN > VTH, the loop

closes,

(

)













+

−

+

=

S

F

TH

IN

TH

O

R

R

V

V

V

V

1

CC is selected to smooth the response of the loop.

+15V

–15V

Ra

Rb1

2

VIN

GND

VO

TRIM

TEMP

6

5

3

4

Rbp

1.5kΩ

50kΩ

Rc

0.1µF

0.1µF

VOUT

OP77

REF-02

Figure 37. Precision Temperature Sensor

Table 8. Resistor Values

TCVOUT Slope (S)

10 mV/°C

100 mV/°C

10 mV/°F

Temperature Range

−55°C to

+125°C

−55°C to

+125°C

−67°F to

+257°C

Output Voltage

Range

−0.55 V to

+1.25 V

−5.5 V to

+12.5V

−0.67 V to

+2.57V

Zero-Scale

0 V @ 0°C

0 V @ 0°C

0 V @ 0°F

Ra (±1% Resistor)

9.09 kΩ

15 kΩ

7.5 kΩ

Rb1 (±1% Resistor)

1.5 kΩ

1.82 kΩ

1.21 kΩ

Rbp (Potentiometer)

200 Ω

500 Ω

200 Ω

Rc (±1% Resistor)

5.11 kΩ

84.5 kΩ

8.25 kΩ

7

1

8

3

2

4

OUTPUT

6

R9

R5

C3

C1

C2

R7

R8

R6

Q19

Q18

Q20

Q16

Q17

Q11 Q12

Q10

Q9

Q13

Q27

Q4

Q3

Q8

Q5

R3

R2A1

R1A

R2B1

R1B

R4

Q1

Q23

Q7

Q24

Q21

Q22

Q6

Q2

Q26

Q25

Q14

Q15

R10

V+

V–

NONINVERTING

INPUT

INVERTING

INPUT

1R2A AND R2B ARE ELECTRONICALLY ADJUSTED ON CHIP AT FACTORY.

(OPTIONAL

NULL)

Figure 38. Simplified Schematic