OP77
C
+15V
0.1µF
C
+15V
0.1µF
R
F
2
100kΩ
V
IN
R
R
c
a
6
5
R
V
O
S
D1
1N4148
1kΩ
2
3
7
50kΩ
TRIM
V
TH
6
R1
2kΩ
V
OUT
OP77
REF-02
V
OUT
R
R
OP77
b1
V
1.5kΩ
IN
3
4
TEMP
GND
4
0.1µF
0.1µF
bp
–15V
–15V
Figure 36. Precision Threshold Detector/Amplifier
Figure 37. Precision Temperature Sensor
When VIN < VTH, amplifier output swings negative, reversing the
biasing diode D1. VO = VTH if RL= ∞ when VIN > VTH, the loop
closes,
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
⎛
⎞
⎟
⎟
⎠
RF
RS
⎜
VIN − VTH 1+
VO = VTH
+
(
)
⎜
Output Voltage
Range
−0.55 V to
+1.25 V
−5.5 V to
+12.5V
−0.67 V to
+2.57V
⎝
CC is selected to smooth the response of the loop.
Zero-Scale
0 V @ 0°C
9.09 kΩ
1.5 kΩ
200 Ω
5.11 kΩ
0 V @ 0°C
15 kΩ
0 V @ 0°F
7.5 kΩ
Ra ( 1% Resistor)
Rb1 ( 1% Resistor)
Rbp (Potentiometer)
Rc ( 1% Resistor)
1.82 kΩ
500 Ω
1.21 kΩ
200 Ω
84.5 kΩ
8.25 kΩ
7
V+
1
(OPTIONAL
NULL)
1
R2A
R2B
R1B
R7
C1
1
8
R1A
Q19
Q9
Q10
Q11 Q12
C2
R9
6
Q7
Q8
OUTPUT
Q3 Q6
Q4
Q5
Q17
C3
R5
R10
Q27
Q16
Q15
3
2
R3
R4
NONINVERTING
INPUT
Q20
Q26
Q25
Q1
Q21
Q22
Q23
Q24
INVERTING
INPUT
Q2
Q18
Q14
R6 R8
Q13
4
V–
1
R2A AND R2B ARE ELECTRONICALLY ADJUSTED ON CHIP AT FACTORY.
Figure 38. Simplified Schematic
Rev. E | Page 14 of 16
ADI [ ADI ]
