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Электронный компонент: HYC9088A

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HYC9088A
Half Height
ARCNET Twisted Pair and Coaxial Compatible
High Impedance Transceiver HIT
FEATURES

ARCNET on Twisted Pair or Coaxial Cable
Drives Shielded and Unshielded Twisted Pair
Cable or Coaxial Cable
Compatible with Existing ARCNET
Installations
2.5 Mbps operation
Pin Compatible with the ARCNET HYC9068
LAN Driver with the Addition of a Single
Terminating Resistor
Supports Star, Bus, and Daisy Chained
Configurations
Enhanced Built-in Filters for Reduced EMI
Twenty Pin Single In-Line Package
Straight or Right Angle Lead Frame
New Reduced Size
GENERAL
DESCRIPTION
The HYC9088 Twisted Pair and Coaxial
Compatible High Impedance Transceiver (HIT) is
a hybrid module that interfaces an ARCNET Local
Area Network controller to one twisted pair or
coaxial cable. The HIT interfaces directly with
Standard Microsystems Corporation's ARCNET
LAN controllers operating at 2.5 Mbps and
connects to a variety of shielded and unshielded
twisted pair or coaxial cables via an on-board
transformer. The network topologies supported by
the HIT are daisy chain, star, and bus
configurations.

During data transmission, the HIT converts the
digital pulse information provided by the LAN
controller into analog signals and drives them onto
the cable. The transmitted signals are filtered to
eliminate undesirable frequencies. The receiver
section of the HYC9088 identifies dipulse signals
on the cable and converts them into TTL signals to
be supplied to the LAN controller.

The HIT supports ARCNET's Dipulse Encoding
Scheme and, is 100% compatible with all existing
coax-based ARCNET networks. This provides an
ARCNET network designer with flexibility to easily
combine coax and twisted pair cabling.

The HYC9088 is pin compatible with the HYC9058
High Impedance Transceiver and is pin compatible
with the HYC9068 LAN Driver with the addition of
a single terminating resistor.
2
TABLE OF CONTENTS

FEATURES...................................................................................................................................................... 1
GENERAL DESCRIPTION.............................................................................................................................. 1
PIN CONFIGURATION.................................................................................................................................... 3
DESCRIPTION OF PIN FUNCTIONS............................................................................................................ 4
FUNCTIONAL DESCRIPTION........................................................................................................................ 5
APPLICATION INFORMATION ..................................................................................................................... 5
OPERATIONAL DESCRIPTION .................................................................................................................. 11
MAXIMUM
GUARANTEED RATINGS..........................................................................................11
DC ELECTRICAL CHARACTERISTICS...................................................................................... 11






3
PIN CONFIGURATION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
NC
NC
VDD
GND
NC
VCC
RX
TPA
NC
TPD
PH-B/SHIELD
PH-A/CENTER
GND
GND
TPC
TPB
GND
nPULSE2
DISABLE
nPULSE1
PACKAGE: 20-Pin SIP
Ordering Information:
HYC9088AR for right angle lead frame
HYC9088AS for straight lead frame
T
O
P
V
I
E
W
Pin 1 Designator
4
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
NAME
SYMBOL
DESCRIPTION
1, 2, 5, 9 No Connect NC
Not used. Make no connection to these pins.
3 Power
Supply
VDD
-5 Volts power supply.
4, 13, 14,
17
Ground GND Ground.
6 Power
Supply
VCC
+5 Volts power supply.
7 Receive
Data
RX
Output. This signal carries the TTL receive pulse information
to the ARCNET LAN Controller Device.
8, 16, 15,
10
Test Points
TPA, TPB,
TPC, TPD
Test points. Make no connection to these pins.
11 Phase-B/
Shield
PH-B/
SHIELD
Output. Connect this signal to Twisted Pair Connector pin 3 or
the shield of the coaxial cable.
12 Phase-A/
Center
PH-A/
CENTER
Output. Connect this signal to Twisted Pair Connector pin 2 or
the center of the coaxial cable.
18
nPulse 2
nPULSE2
Input. This signal is supplied by the ARCNET LAN Controller
Device.
19 Disable
TX
DISABLE
TRANSMIT
Input. A high level on this signal disables the transmit section
of the HYC9088. It is normally connected to ground.
20
nPulse 1
nPULSE1
Input. This signal is supplied by the ARCNET LAN Controller
Device.
5
FUNCTIONAL
DESCRIPTION

The HIT integrates a host of discrete components
into a hybrid module and provides the Local Area
Network designer with space and cost savings as
well as the enhanced reliability of a single
component. Since the HIT is a high impedance
transceiver, it does not disturb the characteristic
impedance of the cable used to interconnect
ARCNET nodes. The two far ends of the twisted
pair cable must be terminated using terminating
resistors equal to the characteristic impedance of
the cable. The HIT is made up of a transmit
section and a receive section. (Please refer to
Figure 1).

Transmit Section

The ARCNET LAN controller transmits a logic "1"
by generating two 100 ns non-overlapping
negative pulses, nPULSE1 and nPULSE2. These
signals are converted by the HIT into a 200 ns
dipulse signal. The HIT shapes the 200 ns signal
into a single cycle of a 5 MHz sine-wave and filters
higher frequency components. The dipulse signal
is then transformer-coupled onto the cable and
has a minimum voltage output of
16 Volts peak-to-peak. The exact output voltage of
the HIT will vary depending on the characteristic
impedance of the cable used. The driving circuitry
of the HIT has been designed to present a high
impedance on the cable in order to minimize
loading.

The DISABLE input of the HYC9088 can be used
to prevent the device from transmitting. During
normal operation, the DISABLE input is tied to
ground.

Receiver Section

The received dipulse signal from the cable is
electrically isolated through the use of a
transformer. This signal is passed through a filter
which eliminates out of band noise. The receive
signal is then fed to a comparator which converts it
into a TTL signal ready to be applied to the LAN
controller chip. The comparator compares the
received signal to an internal voltage threshold to
distinguish noise from real signal.

APPLICATION
INFORMATION

Small Twisted Pair Networks

The HIT eliminates the need for active hubs in
small ARCNET networks. For example, a ten
node ARCNET network can be constructed by
connecting ten HITs using a daisy-chained or bus
configuration (see Figure 2). Note that both
extremes of the cable must be terminated with a
resistor which matches the characteristic
impedence of the Twisted Pair Cable. For the
cable types specified in Table 1, the maximum
length of the twisted pair cable recommended is
400 feet.
Small Coax Network

No active hub is required for an ARCNET network
consisting of eight nodes or less using the
HYC9088 for coax cable (See Figure 2A). Both
ends of the cable must be terminated with a
resistor which matches the characteristic
impedance of the coax cable. For the RG62 cable
specified in Table 1, the maximum length of the
coax cable recommended is 1000 feet.