9

Application Information

The HCPL-8100 and HCPL-

0810 are designed to work

with various transceivers and

can be used with a variety of

modulation methods including

Figure 17. Schematic of HCPL-8100 or HCPL-0810 application for FSK modulation scheme.

Line Driver

The line driver is capable of

driving powerline load

impedances with output signals

biasing of the line driver is

controlled externally via a

pin 4 to ground. The optimum

biasing point value for

modulation frequencies up to

150 kHz is 24 k

Ω. For higher

frequency operation with

certain modulation schemes, it

may be necessary to reduce

the resistor value to enable

compliance with international

regulations.

The output of the line driver

is coupled onto the powerline

using a simple LC coupling

circuit as shown in Figure 18.

Refer to Table 1 for some

typical component values.

Capacitor C2 and inductor L1

attenuate the 50/60 Hz

powerline transmission

frequency. A suitable value for

L1 can range in value from

200 µH to 1 mH. To reduce

the series coupling impedance

at the modulation frequency,

L2 is included to compensate

the reactive impedance of C2.

This inductor should be a low

resistive type capable of

meeting the peak current

requirements. To meet many

regulatory requirements,

capacitor C2 needs to be an

X2 type. Since these types of

capacitors typically have a

very wide tolerance range of

20%, it is recommended to use

as low Q factor as possible for

the L2/C2 combination. Using

a high Q coupling circuit will

result in a wide tolerance on

the overall coupling

impedance, causing potential

communication difficulties with

low powerline impedances.

Occasionally with other circuit

configurations, a high Q

coupling arrangement is

recommended, e.g., C2 less

than 100 nF. In this case it is

Table 1. Typical component values

for LC coupling network.

Figure 18. LC coupling network.

GND

Tx

X2

C2

N

L2

L1

L

1 µF

C3

Carrier

Frequency (kHz)

LC Coupling

L2 (µH) C2 (nF)

110

15

150

120

10

220

132

6.8

220

150

6.8

220

ASK, FSK and BPSK. Figure 17

shows a typical application in

a powerline modem using

Frequency Shift Keying (FSK)

modulation scheme.

normally used as a

compromise to filter out of

band harmonics originating

from the line driver. This is

not required with the HCPL-

8100 or HCPL-0810.

N

1 µF

C3

R1

5 V

C2

330 µH

L1

R3

2

Ω

F ilter

Gain =

− R2 / R1

R2

L2

L

24 k

Ω

HCPL - 8100/0810

1

2

3

4

5

6

7

8

Status

Tx-en

Tx-in

R ref

GND

GND

Tx -out

PLM

Transceiver

STATUS

TX-EN

TX

D1

C4

100 nF

100 nF

C1

C5

100 µF

X2