Table 2. External Clock/Crystal Select
Output
DVDDD
10BASE-T PDX Block Power
+3.3 V Power
Input Pin
Pin
XCLK/XTAL
Clock Source
This pin supplies power to the 10 Mbps Transceiver
block. It must be connected to a +3.3 V ±300 mV
source. This pin requires careful decoupling to ensure
proper device performance.
XTAL1
XTAL2
0
20-MHz Crystal
60-MHz Oscillator/
External CLK
Source
XTAL1
Don’t Care
1
DVDDRX, DVDDTX
10BASE-T I/O Buffer Power
+3.3 V Power
XTAL1
These pins supply power to the 10BASE-T input/output
buffers. They must be connected to a +3.3 V ±300 mV
source. These pins require careful decoupling to en-
sure proper device performance.
Crystal Oscillator In
Input
The internal clock generator utilizes either a 20-MHz
crystal that is attached to pins XTAL1 and XTAL2 or a
60-MHz clock source connected to XTAL1. This pin is
not 5 V tolerant, and the 60 MHz clock source must be
from a 3.3 V source.
DVDDA
Analog PLL Power
+3.3 V Power
This pin supplies power to the IREF current reference
circuit and the 10BASE-T analog PLL. They must be
connected to a +3.3 V ±300 mV source. These pins re-
quire careful decoupling to ensure proper device per-
formance.
XTAL2
Crystal Oscillator Out
Output
The internal clock generator utilizesd a 20-MHz crystal
that is attached to pins XTAL1 and XTAL2.
Power Supply
VDDB
DVSSX, DVSSA
10BASE-T PDX Analog Ground
Ground
These pins are the ground connection for the analog
section within the Physical Data Transceiver (PDX)
block.
I/O Buffer Power (5 Pins)
+3.3 V Power
These pins are the power supply pins that are used by
the input/output buffer drivers. All VDDB pins must be
connected to a +3.3 V supply.
DVSSD
VDD_PCI
10BASE-T PDX Digital Ground
Ground
This pin is the ground connection for the digital logic
within the PDX block.
PCI I/O Buffer Power (9 Pins)
+3.3 V Power
These pins are the power supply pins that are used by
the PCI input/output buffer drivers (except PME driver).
All VDD_PCI pins must be connected to a +3.3 V sup-
ply.
VDDCO
Crystal
+3.3 V Power
This pin supplies power to the crystal circuit.
VSSB
VDDHR
I/O Buffer Ground (15 Pins)
Ground
HomePNA Digital Power
+3.3 V Power
These pins are the ground pins that are used by the
input/output buffer drivers.
These pins are the digital power supply pins that are
used by the internal digital circuitry for the HomePNA
block. They must be connected to a +3.3 V source.
VDD
Digital Power (7 Pins)
+3.3 V Power
VSSHR
These pins are the power supply pins that are used by
the internal digital circuitry. All VDD pins must be con-
nected to a +3.3 V supply.
HomePNA Analog Ground
Ground
This pin is the ground connection for the analog section
within the HomePNA block.
VSS
DVDDA_HR
Digital Ground (7 Pins)
Ground
HomePNA Analog Power
+3.3 V Power
There are seven ground pins that are used by the inter-
nal digital circuitry.
This pin supplies power to the analog section of the
HomePNA block. It must be connected to a +3.3 V
±300 mV source. This pin requires careful decoupling
to ensure proper device performance.
32
Am79C978
AMD [ AMD ]
