OP77
Rev. E | Page 14 of 16
00
32
0-
03
8
+15V
–15V
RS
1k
R1
2k
CC
RF
100k
D1
1N4148
7
6
4
2
3
0.1F
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
V
1
C
00
32
0-
03
9
+15V
–15V
Ra
Rb1
2
VIN
GND
VO
TRIM
TEMP
6
5
3
4
Rbp
1.5k
50k
Rc
0.1F
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°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
C
is selected to smooth the response of the loop.
00
32
0-
00
3
7
18
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