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Preliminary Spec. ver
1.4
KS8910 100/10 Mbps ETHERNET TRANSCEIVER
5
10 BASE-T DIGITAL BLOCKS
OVERVIEW
The 10BASE-T Ethernet Interface Transceiver subsystem performs the physical layer signaling (PSL) and Media
Attachment Unit (MAU) functions as defined by the IEEE 802.3 specification. It functions as a PLS-only device as
an Integrated PLS/MAU (for use with 10BASE-T twisted-pair networks).
The 10BASE-T Ethernet interfaces a back-end controller to a twisted-pair (TP) cable. The controller interface
includes transmit and receive clock and NRZ data channels, as well as mode control logic and signaling. The
twisted-pair interface comprises two circuits: Twisted-Pair Input (TPI) and Twisted-Pair Output (TPO). In addition to
the three basic interfaces, the 10BASE-T Transceiver has synthesized clocks derived from a 25 MHz crystal oscil-
lator and five LED drivers for visual status reporting.
Functions are defined from the back end controller side of the interface. The 10BASE-T Transceiver function refers
to data transmitted to the twisted-pair network (Integrated PLS/MAU mode). The10BASE-T Ethernet Interface
Receive function refers to data received by the back end from the twisted-pair network (Integrated PLS/MAU
mode). In the integrated PLS/MAU mode, the 10BASE-T Ethernet Interface performs all required MAU functions
defined by the IEEE 802.3 10BASE-T specification such as collision detection, link integrity testing, signal quality
error messaging, jabber control and loopback.
TRANSMIT FUNCTION
The 10BASE-T transceiver receives NRZ data from the controller at the TXD input (see 10/100-Mbit/s transceiver
block diagram of KS8920 ), and passes it through a Manchester encoder. The encoded data is transferred to the
twisted-pair network . The advanced integrated pulse shaping and filtering network produces the output signal on
TPON and TPOP, shown in the Chapter 9," Timming" section. The TPO output is pre-distorted and prefiltered to
meet the 10BASE-T jitter template. No external filters are required. During idle periods, the 10BASE-T transceiver
transmits link integrity test pulses on the TPO circuit integrated PLS/MAU mode is selected.
JABBER CONTROL FUNCTION
Figure 5-1 is a state diagram of the 10BASE-T Transceiver Jabber control function. The 10BASE-T Transceiver on-
chip watchdog timer prevents the DTE from locking into a continuous transmit mode. When a transmission exceeds
the time limit, the watchdog timer disables the transmit and loopback functions, and activates the JAB pin. Once the
10BASE-T is in the jabber state, the TXD circuit must remain idle for a period of 0.25 to 0.75 seconds before it will
exit the jabber state.
10BASE-T DIGITAL BLOCKS
5-1
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