Circuit diagrams and other information relating to SMSC products are included as a means of illustrating typical applications. Consequently, complete
information sufficient for construction purposes is not necessarily given. Although the information has been checked and is believed to be accurate, no
responsibility is assumed for inaccuracies. SMSC reserves the right to make changes to specifications and product descriptions at any time without
notice. Contact your local SMSC sales office to obtain the latest specifications before placing your product order. The provision of this information
does not convey to the purchaser of the described semiconductor devices any licenses under any patent rights or other intellectual property rights of
SMSC or others. All sales are expressly conditional on your agreement to the terms and conditions of the most recently dated version of SMSC's
standard Terms of Sale Agreement dated before the date of your order (the "Terms of Sale Agreement"). The product may contain design defects or
errors known as anomalies which may cause the product's functions to deviate from published specifications. Anomaly sheets are available upon
request. SMSC products are not designed, intended, authorized or warranted for use in any life support or other application where product failure
could cause or contribute to personal injury or severe property damage. Any and all such uses without prior written approval of an Officer of SMSC
and further testing and/or modification will be fully at the risk of the customer. Copies of this document or other SMSC literature, as well as the Terms
of Sale Agreement, may be obtained by visiting SMSC’s website at http://www.smsc.com. SMSC is a registered trademark of Standard Microsystems
Corporation (“SMSC”). Product names and company names are the trademarks of their respective holders.
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DAMAGES.
Revision (02-16-07)
Page 2
SMSC HYC9088A
DATASHEET
PIN CONFIGURATION
Pin 1 Designator
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
R
TPA
NC
TPD
PH-B/SHIELD
PH-A/CENTER
GND
GND
TPC
TPB
GND
nPULSE2
DISABLE
nPULSE1
T
O
P
V
I
E
W
PACKAGE: 20-Pin SIP
Revision (02-16-07)
Page 3
SMSC HYC9088A
DATASHEET
DESCRIPTION OF PIN FUNCTIONS
PIN NO.
1, 2, 5, 9
3
4, 13, 14,
17
6
7
8, 16, 15,
10
11
12
18
19
20
NAME
No Connect
Power
Supply
Ground
Power
Supply
Receive
Data
Test Points
Phase-B/
Shield
Phase-A/
Center
nPulse 2
Disable TX
nPulse 1
SYMBOL
NC
VDD
GND
VCC
RX
TPA, TPB,
TPC, TPD
PH-B/
SHIELD
PH-A/
CENTER
nPULSE2
DISABLE
TRANSMIT
nPULSE1
DESCRIPTION
Not used. Make no connection to these pins.
-5 Volts power supply.
Ground.
+5 Volts power supply.
Output. This signal carries the TTL receive pulse information
to the ARCNET LAN Controller Device.
Test points. Make no connection to these pins.
Output. Connect this signal to Twisted Pair Connector pin 3 or
the shield of the coaxial cable.
Output. Connect this signal to Twisted Pair Connector pin 2 or
the center of the coaxial cable.
Input. This signal is supplied by the ARCNET LAN Controller
Device.
Input. A high level on this signal disables the transmit section
of the HYC9088. It is normally connected to ground.
Input. This signal is supplied by the ARCNET LAN Controller
Device.
Revision (02-16-07)
Page 4
SMSC HYC9088A
DATASHEET
FUNCTIONAL DESCRIPTION
The HYC9088A 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.
Combination of Twisted Pair and Coax
Networks
A Two-Port Link is used to combine twisted pair network and a coax network. A Two-Port Link has a coax connector on
one side and two modular jacks on the other and contains the proper impedance-matching circuitry. Refer to Figure 3 for
an illustration of a twisted pair network combined with a coaxial network.
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