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
Gain =
−
R2 / R1
STATUS
TX-EN
TX
PLM
Transceiver
F ilter
100 nF
R
ref
24 kΩ
C1
R1
ASK, FSK and BPSK. Figure 17
shows a typical application in
a powerline modem using
Frequency Shift Keying (FSK)
modulation scheme.
R2
R3
2
Ω
C3
1 µF
L2
5V
C5
100 µF
D1
C2
L
X2
L1
330 µH
N
1
2
3
4
Status
Tx-en
Tx-in
R ref
Tx -out
V
CC
GND
GND
8
7
6
5
C4
100 nF
HCPL - 8100/0810
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
up to 4 V
PP
. The internal
biasing of the line driver is
controlled externally via a
resistor R
ref
connected from
pin 4 to ground. The optimum
biasing point value for
modulation frequencies up to
150 kHz is 24 kΩ. 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
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.
C3
Tx
1 µF
L1
N
GND
X2
L2
C2
L
Figure 18. LC coupling network.
Table 1. Typical component values
for LC coupling network.
Carrier
LC Coupling
Frequency (kHz)
L2 (µH) C2 (nF)
110
15
150
120
10
220
132
6.8
220
150
6.8
220
9
HP [ AGILENT(HEWLETT-PACKARD) ]
