AM79C973KCW Advanced Micro Devices, AM79C973KCW Datasheet - Page 86

• Manufacturer Part Number: AM79C973KCW
• Description: PCnet-FAST III Single-Chip 10/100 Mbps PCI Ethernet Controller with Integrated PHY
• Manufacturer: Advanced Micro Devices

10BASE-T Block
The 10BASE-T block consists of the following sub-
blocks:
Refer to Figure 38 for the 10BASE-T block diagram.
Twisted Pair Transmit Function
Data transmission over the 10BASE-T medium re-
quires use of the integrated 10BASE-T MAU and uses
the differential driver circuitry on the TX± pins.
TX± is a differential twisted-pair driver. When properly
terminated, TX± will meet the transmitter electrical re-
quirements for 10BASE-T transmitters as specified in
86
— Transmit Process
— Receive Process
— Interface Status
— Collision Detect Function
— Jabber Function
— Reverse Polarity Detect
.
SDI+
SDI–
RX+
RX–
0.1 F
TX+
TX–
2 K
1 K
Notes:
50
3.3 V
49.9
50
50
49.9
49.9
1. The isolation transformers include common-mode chokes.
2. Consult magnetics vendors for appropriate termination schemes.
1%
.01 µF
Figure 37. TX± and RX± Termination
.01 µF
P R E L I M I N A R Y
Transformer with
Am79C973/Am79C975
*
common-mode
*
Isolation
1:1.414
chokes
1:1 *
0.001 µF
2KV
(chassis ground)
75
*
IEEE 802.3, Section 14.3.1.2. The load is a twisted pair
cable that meets IEEE 802.3, Section 14.4.
The TX± signal is filtered on the chip to reduce har-
monic content per Section 14.3.2.1 (10BASE-T). Since
filtering is performed in silicon, TX± can be connected
directly to a standard transformer. External filtering
modules are not needed.
Twisted Pair Receive Function
The RX+ port is a differential twisted-pair receiver.
When properly terminated, the RX+ port will meet the
electrical requirements for 10BASE-T receivers as
specified in IEEE 802.3, Section 14.3.1.3. The receiver
has internal filtering and does not require external filter
modules or common mode chokes.
Signals appearing at the RX± differential input pair are
routed to the internal decoder. The receiver function
meets the propagation delays and jitter requirements
specified by the 10BASE-T Standard. The receiver
squelch level drops to half its threshold value after un-
squelch to allow reception of minimum amplitude sig-
75
.01 µF
75
75
(8)
(7)
RX+ (3)
(5)
(4)
RX– (6)
TX+ (1)
TX– (2)
Connector
RJ45
21510D-42