AM79C989JCT Advanced Micro Devices, AM79C989JCT Datasheet - Page 12

• Manufacturer Part Number: AM79C989JCT
• Description: Quad Ethernet Switching Transceiver (QuEST)
• Manufacturer: Advanced Micro Devices

Management Interface
MDC
Management Data Clock
Input
MDC provides the timing reference for data on the
MDIO pin. The Management Interface provides read
and write access to QuEST registers, similar to the MII
management interface of the IEEE 802.3u standard.
MDIO
Management Data I/O
Input/Output
MDIO is a bidirectional data signal between QuEST
and a management entity. MDIO timing is referenced to
MDC. The Management Interface provides read and
write access to QuEST registers, similar to the MII
management interface of the IEEE 802.3u standard.
Miscellaneous Pins
SCLK
System Clock
Input
SLCK is a 40-MHz (100 ppm) clock used for timing the
10BASE-T ports, the (optional) AUI port, the QuASI in-
terface and core logic.
REXT
External Resistor
Input
REXT should be pulled to analog VDD via a 13 K
tolerance) external resistor. This signal is used to deter-
mine the 10BASE-T transmit current reference.
QRST/STRB
QuEST Reset and Channel 0 Strobe
Input
QRST/STRB is an active-low signal that will reset
QuEST if asserted for at least 1 s. QRST/STRB also
forces the channel slots of the QuASI interface to be
continuous aligned if strobed for a single clock period.
Power Pins
VDD
Digital Power
Power
There is a single power supply pin that is used for inter-
nal digital circuitry. The VDD pin must be connected to
a +5 V supply.
12
P R E L I M I N A R Y
(1%
Am79C989
VSS
Digital Ground
Power
There is a single ground pin that is used for internal dig-
ital circuitry. The VSS pin must be connected to ground.
VDDIO
Digital I/O Power
Power
There is a single power supply pin that is used for digi-
tal I/O pins. The VDDIO pin can be connected to either
a +5 V or a +3.3 V supply.
VSSIO
Digital I/O Ground
Power
There is a single ground pin that is used for digital I/O
pins. The VSSIO pin must be connected to ground.
VDDTX
Analog 10BASE-T Power
Power
There are three power supply pins that are used for an-
alog 10BASE-T transmit pins. The VDDTX pins must
be connected to a +5 V supply.
VSSTX
Analog 10BASE-T Ground
Power
There are two ground pins that are used for analog
10BASE-T transmit pins. The VSSTX pins must be
connected to ground.
VSSRX
Analog 10BASE-T Ground
Power
There is a single ground pin that is used for analog
10BASE-T receive pins. The VSSRX pin must be con-
nected to ground.
VSSAUI
Analog I/O Ground
Power
There is a single ground pin that is used for analog AUI
circuitry. The VSSAUI pin must be connected to
ground.