ISO120 9. Right-Leg Driven ECG Amplifier (with defibrillator protection and calibration). Typical Schematic
3θ Y-Connected Power Transformer
+V
S1
+V
S1
–V
S1
+V
S2
–V
S2
1 3 4 15
200kΩ
2
8
+
1
–
7
6
–V
SI
10
9
C
1
2
23
ISO
120
21
24
22
9
16
11
10
13
14
C
2
12
120Vrms
100A
0.005 Power Resistor
0.001µF
200kΩ
V
OUT
C
1
= 1000pF
C
2
= 1000pF
Differential input accurately senses power Resistor voltage.
High frequency spike reject Filter has f
CO
= 400Hz.
FIGURE 8. Isolated Powerline Monitor.
1mV
5MΩ
5.00V
0V
Calibration Signal
C
1
1kΩ
Calibration
+V
S1
1/2W
300kΩ
On
NE2H
(2)
Calibration
1/2W
300kΩ
50kΩ
+V
S1
0.0082
(1)
15
12
4
+
13
7
11
5
10
6
–
8
14
9 0.0082
–V
S1
–V
S1
+V
S1
1/2W
300kΩ
Right Leg
NE2H
–V
S1
+V
S1
180K „¦
7
6
3
4
20pF
–V
S1
1
4
14
1
0.3
NOTE: (1) All Capacitor values in µF unless otherwise
noted. Diodes are IN4148. (2) NE2H: Neon bulb, max
striking voltage 95V
AC
.
16
2
Gain = 1000
20kΩ
29
PWS
726A
32
1
2
39
37
ISO
40
121
38
3
4
21
C
2
22
19
18
20 17
Left ARM
500pF
–V
S1
200pF
50kΩ
+V
S1
24
23
+V
S2
–V
S2
Right ARM
On
NE2H
500pF
–V
S1
+V
S1
20µH
+V
S2
FIGURE 9. Right-Leg Driven ECG Amplifier (with defibrillator protection and calibration).
ISO120 121
12