HCPL-0720-500E Datasheet HCPL-7720-300E, HCPL-0721-000E, HCPL-0720-500E | P13-P15

Optical Isolation for Field Bus Networks

To recognize the full benets of these networks, Avago

optocouplers are recom mended to provide galvanic iso-

lation. As network communication is bi-directional (in-

volving receiving data from and transmitting data onto

the network), two Avago optocouplers are needed. By

providing galvanic isolation, data integrity is retained

via noise reduction and the elimination of false signals.

In addition, the network receives maximum protection

from power system faults and ground loops.

Within an isolated node, such as the DeviceNet Node

shown in Figure 16, some of the node’s components are

referenced to a ground other than V- of the network.

Figure 16. Typical DeviceNet Node

These components could include such things as devices

with serial ports, parallel ports, RS-232 and RS-485 type

ports. As shown in Figure 16, power from the network is

used only for the transceiver and input (network) side of

the optocouplers.

Isolation of nodes connected to any of the three types of

digital eld bus networks is best achieved by using the

HCPL-772X/072X optocouplers. For each network, the

HCPL-772X/072X satisify the critical propagation delay

and pulse width distortion require ments over the tem-

perature range of 0 °C to +85 °C, and power supply volt-

age range of 4.5 V to 5.5 V.

NODE/APP SPECIFIC

µP/CAN

HCPL

772x/072x

HCPL

772x/072x

TRANSCEIVER

LOCAL

NODE

SUPPLY

5 V REG.

NETWORK

POWER

SUPPLY

V+ (SIGNAL)

V– (SIGNAL)

V+ (POWER)

V– (POWER)

GALVANIC

ISOLATION

BOUNDARY

AC LINE

DRAIN/SHIELD

SIGNAL

POWER

Implementing CC-Link with the HCPL-772X/072X

CC-Link (Control and Communication Link) is developed

to merge control and information in the low-level net-

work (eld network) by PCs, thereby making the mul-

tivendor environment a reality. It has data control and

message-exchange function, as well as bit control func-

tion, and operates at the speed up to 10 Mbps.

Figure 17. Recommended CC-Link application circuit

Power Supplies and Bypassing

The recommended CC-Link circuit is shown in Figure

17. Since the HCPL-772X/072X are fully compatible

with CMOS logic level signals, the optocoupler is con-

nected directly to the transceiver. Two bypass capacitors

(with values between 0.01 µF 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 capacitor and the power supply pins should not

exceed 20 mm. The bypass capacitors are required be-

cause of the high speed digital nature of the signals in-

side the optocoupler.

DD1

HCPL-7720#500

0.1 µ

GND

DD2

GND

RD1

10 K

DD1

(5 V)

0.1 µ

GND

DD2

(5 V)

DD2

HCPL-7720#500

0.1 µ

GND

DD1

GND

0.1 µ

OE

HCPL-2611#560

–

0.1 µ

MPU

BOARD

OUTPUT

390

HC14

1 K

OE

HCPL-2611#560

GND

–

0.1 µ

SDGATEON

390

HC14

1 K

10 K

GND

DD

GND

SN75ALS181NS

FIL

SLD

Implementing DeviceNet and SDS with the HCPL-772X/072X

With transmission rates up to 1 Mbit/s, both DeviceNet

and SDS are based upon the same broadcast-oriented,

communica tions protocol — the Controller Area Network

(CAN). Three types of isolated nodes are recommended

for use on these networks: Isolated Node Powered by

the Network (Figure 18), Isolated Node with Transceiver

Providing Power to the Network (Figure 20).

Figure 18. Isolated node powered by the network.

Isolated Node with Transceiver Powered by the Network

Figure 19 shows a node powered by both the network

and another source. In this case, the trans ceiver and iso-

lated (network) side of the two optocouplers are pow-

ered by the network. The rest of the node is powered by

the AC line which is very benecial when an application

requires a signicant amount of power. This method is

also desirable as it does not heavily load the network.

More importantly, the unique “dual-inverting” design of

the HCPL-772X/072X ensure the network will not “lock-

up” if either AC line power to the node is lost or the node

powered-o. Specically, when input power (V

DD1

) to the

HCPL-772X/072X located in the transmit path is eliminat-

ed, a RECESSIVE bus state is ensured as the HCPL-772X/

072X output voltage (V

) go HIGH.

Isolated Node Powered by the Network

This type of node is very exible and as can be seen in

Figure 18, is regarded as “isolated” because not all of its

components have the same ground reference. Yet, all

compo nents are still powered by the network. This node

contains two regulators: one is isolated and powers the

CAN controller, node-specic application and isolated

(node) side of the two optocoup lers while the other is

non-isolated. The non-isolated regulator supplies the

transceiver and the non-isolated (network) half of the

two optocouplers.

*Bus V+ Sensing

It is suggested that the Bus V+ sense block shown in Fig-

ure 19 be implemented. A locally powered node with an

un-powered isolated Physical Layer will accumulate er-

rors and become bus-o if it attempts to transmit. The

Bus V+ sense signal would be used to change the BOI at-

tribute of the DeviceNet Object to the “auto-reset” (01)

value. Refer to Volume 1, Section 5.5.3. This would cause

the node to continually reset until bus power was detect-

ed. Once power was detected, the BOI attribute would

be returned to the “hold in bus-o” (00) value. The BOI

attribute should not be left in the “auto-reset” (01) value

since this defeats the jabber protection capability of the

CAN error connement. Any inexpensive low frequency

optical isolator can be used to implement this feature.

NODE/APP SPECIFIC

µP/CAN

HCPL

772x/072x

HCPL

772x/072x

TRANSCEIVER

REG.

V+ (SIGNAL)

V– (SIGNAL)

V+ (POWER)

V– (POWER)

GALVANIC

ISOLATION

BOUNDARY

DRAIN/SHIELD

SIGNAL

POWER

ISOLATED

SWITCHING

POWER

SUPPLY

NETWORK

POWER

SUPPLY

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18

HCPL-0720-500E

Mfr. #:

Buy HCPL-0720-500E

Manufacturer:

Broadcom / Avago

Description:

High Speed Optocouplers 25MBd 1Ch 150mA

Lifecycle:

New from this manufacturer.

Delivery:

DHL FedEx Ups TNT EMS

Payment:

T/T Paypal Visa MoneyGram Western Union

HCPL-0720-500E

HCPL-0720-500E

Products related to this Datasheet