AM79C98 Advanced Micro Devices, AM79C98 Datasheet - Page 6

• Manufacturer Part Number: AM79C98
• Description: Twisted-Pair Ethernet Transceiver (TPEX)
• Manufacturer: Advanced Micro Devices

6
PIN DESCRIPTION
AV
Analog Power
This pin supplies +5 V to analog portions of the TPEX
circuitry.
AV
Analog Ground
This pin is the ground reference for analog portions of
the TPEX circuitry.
CI+, CI–
Control In
Output
AUI port differential driver.
DI+, DI–
Data In
Output
AUI port differential driver.
DO+, DO–
Data Out
Input
AUI port differential receiver.
DV
Digital Power
This pin supplies +5 V to digital portions of the TPEX
circuitry.
DV
Digital Ground
This pin is the ground reference for digital portions of
TPEX circuitry.
LNKST
Link Status
Open Drain, Input/Output
When this pin is tied LOW, the internal Link Test
Receive function is disabled and the Transmit and Re-
ceive functions will remain active irrespective of arriv-
ing idle Link Test pulses and data. TPEX continues to
generate idle Link Test pulses irrespective of the status
of this pin.
As an output, this pin is driven LOW if the link is identi-
fied as functional. However, if the link is determined to
be nonfunctional, due to missing idle Link Test pulses
or data packets, then this pin is not driven. In the LOW
output state, the pin is capable of sinking a maximum
of 16 mA and can be used to drive an LED.
This pin is internally pulled HIGH when inactive.
DD
SS
DD
SS
Am79C98
PRDN/RST
Power Down/Reset
Input, Active LOW
Driving this input LOW resets the internal logic of TPEX
and places the device in a special Power Down mode.
In the Power Down/Reset mode, all output drivers are
placed in their inactive state.
RCV
Receive
Output
This pin is driven HIGH while TPEX is receiving data on
the RXD pins and is transferring the received signal
onto the AUI DI pair. The RCV and XMT pins are simul-
taneously driven HIGH during collision.
REXT
External Resistor
Input
An external precision resistor is connected between
this pin and AV
ence for the internal voltage-controlled oscillator
(VCO).
RXD+, RXD–
Receive Data
Input
10BASE-T port differential receivers.
RXPOL
Receive Polarity
Open Drain, Input/Output
The twisted-pair receiver is capable of detecting a re-
ceive signal with reversed polarity (wiring error). The
RXPOL pin is normally in the LOW state, indicating cor-
rect polarity of the received signal. If the receiver de-
tects reversed polarity, then this pin is not driven (goes
HIGH) and the polarity of subsequent packets is in-
verted. In the LOW output state, this pin can sink up to
a maximum of 16 mA and is therefore capable of driv-
ing an LED.
This feature can be disabled by strapping this pin LOW.
In this case, the Receive Polarity correction circuit is
disabled and the internal receive signal remains non-
inverted, irrespective of the received signal.
This pin is internally pulled HIGH when inactive.
SQE TEST
Signal Quality Test (Heartbeat) Enable
Input, Active LOW
The SQE Test function is enabled by tying this input
LOW.
This input is internally pulled HIGH when inactive.
DD
in order to provide a voltage refer-