HCPL-0721 datasheet(16/18 Pages) HP

16 / 18 page

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

optocoupler is connected directly

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) establishes the

connection of a field automation

unit (control or central processing

station) or a field device to the

transmission medium. The PBC

consists of the line transceiver,

optical isolation, frame character

transmitter/receiver (UART), and

the FDL/APP processor with the

interface to the PROFIBUS user.

to the CAN transceiver. Two

bypass capacitors (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

PROFIBUS USER:

CONTROL STATION

(CENTRAL PROCESSING)

OR FIELD DEVICE

USER INTERFACE

FDL/APP

PROCESSOR

TRANSCEIVER

OPTICAL ISOLATION

UART

PBC

MEDIUM

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.

VDD1

VIN

GND1

VDD2

GND2

HCPL-772x

HCPL-072x

GND2

VDD2

GND1

VIN

VDD1

HCPL-772x

HCPL-072x

GND

ISO 5 V

0.01 µF

RX0

0.01 µF

TX0

0.01

µF

0.01

µF

TxD

CANH

REF

RXD

82C250

VCC

GND

CANL

0.01 µF

VREF

LINEAR OR

SWITCHING

REGULATOR

5 V

1 M

0.01 µF

500 V

30 V

5 V+

4 CAN+

3 SHIELD

2 CAN–

1 V–

GALVANIC

ISOLATION

BOUNDARY

Figure 22. PROFIBUS Controller (PBC).

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