Avago Technologies ACPL-224-500E - Manual (Page 44)

AV02-4387EN 41 Avago Technologies
Isolation Amplifier for Bipolar Signals - Circuit No. 2
Description
This circuit shows how bipolar
analog signals can be transmitted
across an isolation boundary by
using just one HCNR200 opto coup-
ler. This circuit provides an easy in-
terface to A/D converters with two
output signals: an analog signal pro-
portional to the magni tude of the
input signal, and a digital signal cor-
responding to the Sign of the input
signal. The HCNW138 optocoupler,
which couples the Sign signal, can
be substituted with a faster opto-
coupler in case the Sign changes
faster than 50 kHz.
References
HCNR200/1 Technical Data
Alternative Avago Parts
1) HCPL-7800A, HCPL-7800, HCPL-
7840 Isolation Amplifier
2) HCNW2601 High Speed Digital
Optocoupler (for the Sign signal)
3) HCPL-785X Hermetically Sealed
Isolation Amplifier
Performance of Optocoupler
• 0.01% nonlinearity
• Wide bandwidth: dc to 1 MHz
• Low transfer gain variation: ±5%
(K3 of HCNR201)
Benefits
• Low drift
• Very low offset
Analog Applications
–
+
V MAGNITUDE
–
+
V IN
+
–
GAIN
CONTROL
–
+
+
–
V CC
V
SIGN
CNR201
LED
6N138
D4
10 pF
R4
680 k Ω
R5
180 k Ω
D1
D2
D3
R3
4.7 k Ω
R2
10 k Ω
R7
10 k Ω
C2 10 pF
C3 10 pF
R8
2.2 k Ω
R6
50 k Ω