IC-HF Datasheet, PDF (9/36 Pages) IC-Haus GmbH – 6-CH. ENCODER LINK, RS-422 DRIVER/RECEIVER

iC-HF
preliminary
6-CH. ENCODER LINK, RS-422 DRIVER/RECEIVER
CHANNEL DESCRIPTION
Rev C1, Page 9/36
iC-HF is a 6-channel RS-422 line driver.
There are two types of channels:
• unidirectional channel
• bidirectional channel
This configuration is useful for calibrating sensors. Ana-
log signals from the sensor can be directly accessed
from pins Qi/NQi. More information on the Encoder
Link State on page 20.
Unidirectional channel
Xi
Channels 1, 2 and 3 are unidirectional channels. These
NXi
channels can work under unidirectional RS-422 driver
configuration or under Encoder Link State.
Encoder Link
Qi
NQi
Xi
BYP
NXi
RS422
Qi
TRI
NQi
Figure 1: Unidirectional channel
Figure 3: Equivalent circuit of 1 channel (2 lines) in
Encoder Link State
Bidirectional channel
When the channel works as unidirectional RS-422
driver, single ended input signals at Xi pins are con-
verted into differential output signals at Qi/NQi outputs.
Output signals follow RS-422 protocol. Differential out-
put drivers are tristate drivers. OEN pin must be set
hi to enable differential output signals, otherwise they
will remain in high impedance state. More information
on the internal signal TRI and the output drivers in high
impedance can be found on page 16.
A pull-down resistor is present at the inputs, and in-
coming signals at Xi pins must be TTL-compatible. In
unidirectional driver configuration, signals at NXi pins
are disabled. The equivalent circuit can be found in
figure 2.
Channels 4, 5 and 6 are bidirectional channels. These
channels can work under bidirectional RS-422 driver
configuration or under Encoder Link state.
Xi
BYP
EBIS
RS422 I/O
Qi
TRI
NQi
+
_
Figure 4: Bidirectional channel
When the channel is a bidirectional RS-422 driver, it
RS422 output
Xi
Qi
can work as a transmitter or as a receiver. It cannot
NXi
TRI
NQi
work simultaneously in both modes, each working mode
corresponds to a specific configuration of the channel.
Figure 2: Equivalent circuit of unidirectional RS-422
driver channel
When the channel is in Encoder Link State, signals
present at input pins Xi are bypassed and directly con-
nected to output pins Qi. Signals at NXi are bypassed
too to output pins NQi. Unidirectional channels in En-
coder Link State present two bypassed lines.
The input stage and the input pull-down resistor and
the output stage are disabled in Encoder Link State.
If the channel is a transmitter, single ended signals at
input pins Xi are converted into differential output sig-
nals at Qi/NQi outputs. Outputs signals follow RS-422
protocol. A pull-down resistor is present at the inputs,
and incoming signals at Xi pins must be TTL compatible.
The equivalent circuit can be found in figure 5. Similarly
to unidirectional channels, OEN pin must be set hi to
enable differential output signals, otherwise they will
remain in high impedance state. More information on
output drivers in high impedance can be found on page
16.