AM79C978 Advanced Micro Devices, AM79C978 Datasheet - Page 32

• Manufacturer Part Number: AM79C978
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: Advanced Micro Devices

XTAL1
Crystal Oscillator In
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.
XTAL2
Crystal Oscillator Out
The internal clock generator utilizesd a 20-MHz crystal
that is attached to pins XTAL1 and XTAL2.
Power Supply
VDDB
I/O Buffer Power (5 Pins)
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.
VDD_PCI
PCI I/O Buffer Power (9 Pins)
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.
VSSB
I/O Buffer Ground (15 Pins)
These pins are the ground pins that are used by the
input/output buffer drivers.
VDD
Digital Power (7 Pins)
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.
VSS
Digital Ground (7 Pins)
There are seven ground pins that are used by the inter-
nal digital circuitry.
32
XTAL1
XTAL1
Input Pin
Table 2. External Clock/Crystal Select
Don’t Care
Output
XTAL2
Pin
XCLK/XTAL
0
1
60-MHz Oscillator/
20-MHz Crystal
Clock Source
External CLK
+3.3 V Power
+3.3 V Power
+3.3 V Power
Source
Ground
Ground
Output
Input
Am79C978
DVDDD
10BASE-T PDX Block Power
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.
DVDDRX, DVDDTX
10BASE-T I/O Buffer Power
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.
DVDDA
Analog PLL 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.
DVSSX, DVSSA
10BASE-T PDX Analog Ground
These pins are the ground connection for the analog
section within the Physical Data Transceiver (PDX)
block.
DVSSD
10BASE-T PDX Digital Ground
This pin is the ground connection for the digital logic
within the PDX block.
VDDCO
Crystal
This pin supplies power to the crystal circuit.
VDDHR
HomePNA Digital Power
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.
VSSHR
HomePNA Analog Ground
This pin is the ground connection for the analog section
within the HomePNA block.
DVDDA_HR
HomePNA Analog Power
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.
+3.3 V Power
+3.3 V Power
+3.3 V Power
+3.3 V Power
+3.3 V Power
+3.3 V Power
Ground
Ground
Ground