Datasheet

18
Power Supplies and Bypassing
The recommended DeviceNet application circuit is
shown in Figure 21. Since the HCPL-772X/072X are fully
compatible with CMOS logic level signals, the optocoup-
ler is connected directly to the CAN transceiver. Two by-
pass capacitors (with values between 0.01 and 0.1 µF)
are required and should be located as close as possible
Figure 21. Recommended DeviceNet application circuit.
Implementing PROFIBUS with the HCPL-772X/072X
An acronym for Process Fieldbus, PROFIBUS is essentially
a twisted-pair serial link very similar to RS-485 capable
of achieving high-speed communication up to 12 MBd.
As shown in Figure 22, a PROFIBUS Controller (PBC) es-
tablishes the connection of a eld automation unit (con-
trol or central processing station) or a eld device to
the transmission medium. The PBC consists of the line
transceiver, optical isolation, frame character transmit-
ter/receiver (UART), and the FDL/APP processor with the
interface to the PROFIBUS user.
PROFIBUS USER:
CONTROL STATION
(CENTRAL PROCESSING)
OR FIELD DEVICE
USER INTERFACE
FDL/APP
PROCESSOR
TRANSCEIVER
OPTICAL ISOLATION
UART
PBC
MEDIUM
HCPL-0710 fig 22
HCPL-0710 fig 21
8
7
6
1
3
5
2
4
V
DD1
V
IN
GND
1
V
DD2
V
O
GND
2
HCPL-772x
HCPL-072x
4
3
2
5
7
1
6
8
GND
2
V
O
V
DD2
GND
1
V
IN
V
DD1
HCPL-772x
HCPL-072x
GND
ISO 5 V
ISO 5 V
0.01 µF
RX0
0.01 µF
TX0
0.01
µF
0.01
µF
TxD
CANH
REF
RXD
82C250
V
CC
GND
Rs
CANL
C4
0.01 µF
+
VREF
LINEAR OR
SWITCHING
REGULATOR
5 V
5 V
+ +
R1
1 M
C1
0.01 µF
500 V
D1
30 V
5 V+
4 CAN+
3 SHIELD
2 CAN–
1 V–
GALVANIC
ISOLATION
BOUNDARY
Figure 22. PROFIBUS Controller (PBC).
to the input and output power-supply pins of the HCPL-
772X/072X. For each capacitor, the total lead length be-
tween 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.