Avago Technologies ACPL-224-500E - Manual (Page 43)

AV02-4387EN 40 Avago Technologies
Isolation Amplifier for Bipolar Signals - Circuit No. 1
Description
This circuit shows how the HCNR200
High Linearity Opto coupler can be
used for trans mit ting bipolar analog
signals across an isolation boundary.
This circuit uses two optocouplers:
OC1 and OC2; OC1 handles the posi-
tive portions of the input signal and
OC2 handles the negative portions.
Diodes D
1
and D
2
help reduce cross-
over distor tion by keeping both am-
plifiers active during both positive
and negative portions of the input
signal.
Performance of Circuit
• 0.01% nonlinearity
• Bandwidth: dc to 100 Hz
• Low transfer gain variation: ±5%
(K3 of HCNR201)
Benefits
• Low drift
• Low crossover distortion within
the dc to 100 Hz frequency band
• Good linearity
• Very low offset
References
HCNR200/1 Technical Data
Alternative Avago Parts
1) HCPL-7800A, HCPL-7800, HCPL-
7840 Isolation Amplifier
2) HCPL-785X Hermetically Sealed
Isolation Amplifier
Analog Applications
–
+
V OUT
–
+
V
IN
OC1
PD1
+
–
OC2
PD1
R1
50 k Ω
BALANCE
D2
C2 10 pF
C1 10 pF
D1 R4
680 Ω
R5
680
OC1
LED
OC2
LED
R3
180 k Ω
R2
180 k Ω
C3 10 pF
OC1
PD2
R6
180 k Ω
R7
50 k Ω
GAIN
OC2
PD2
8
7
6
1
3
HCNR200/1
5
2
4
LED
NC
NC
PD1 PD2
K1 K2
ISOLATION
BARRIER