Datasheet
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Data subject to change. Copyright © 2005-2008 Avago Technologies Limited. All rights reserved. Obsoletes AV01-0565EN
AV02-0876EN - June 10, 2008
Power Supplies and Bypassing
The recommended PROFIBUS application circuit is shown
in Figure 23. Since the HCPL-772X/072X are fully com-
patible with CMOS logic level signals, the optocoupler is
connected directly to the transceiver. Two bypass capac-
itors (with values between 0.01 and 0.1 µF) are required
and should be located as close as possible to the input
and output power-supply pins of the HCPL-772X/072X.
For each capacitor, the total lead length between both
ends of the capacitor and the power supply pins should
not exceed 20 mm. The bypass capacitors are required
because of the high-speed digital nature of the signals
inside the optocoupler.
Being very similar to multi-station RS485 systems, the
HCPL-061N optocoupler provides a transmit disable
function which is necessary to make the bus free after
each master/slave transmission cycle. Specically, the
HCPL-061N disables the transmitter of the line driver by
putting it into a high state mode. In addition, the HCPL-
061N switches the RX/TX driver IC into the listen mode.
The HCPL-061N oers HCMOS compatibility and the
high CMR performance (1 kV/µs at V
CM
= 1000 V) es-
sential in industrial communication interfaces.
Figure 23. Recommended PROFIBUS application circuit.
HCPL-0710 fig 23
1
2
3
8
6
4
7
5
V
DD2
V
O
GND
2
V
DD1
V
IN
GND
1
HCPL-772x
HCPL-072x
8
7
6
1
3
5
2
4
V
DD1
V
IN
GND
1
V
DD2
V
O
GND
2
HCPL-772x
HCPL-072x
5 V
0.01 µF
0.01 µF
0.01
µF
0.01
µF
R
A
SN75176B
V
CC
GND
DE
B
0.01
µF
ISO 5 V
1 M
0.01 µF
+
–
GALVANIC
ISOLATION
BOUNDARY
5 V ISO 5 V
RE
D
1
4
3
2
Rx
ISO 5 V
Tx
8
7
6
1
3
5
2
4
ANODE
V
CC
V
O
GND
5 V
0.01
µF
ISO 5 V
Tx ENABLE
CATHODE
V
E
680 Ω
HCPL-061N
1, 0 kΩ
5
7
6
8
RT
SHIELD