IP101A LF
Data Sheet
21/36
Oct 22, 2007
Copyright © 2004, IC Plus Corp.
IP101A LF-DS-R12
3
Functional Description
IP101A LF 10/100Mbps Ethernet PHY Transceiver integrates 100 Base-TX and 10 Base-T modules into a
single chip. IP101A LF acts as an interface between physical signaling and Media Access Controller
(MAC).
IP101A LF has several major functions:
1. PCS layer (Physical Coding Sub-Layer): This function contains transmit, receive and carrier sense
functional circuitries.
2. Management interface: Media Independent Interface (MII) or Reduced Management Interface (RMII)
registers contains information for communication with other MAC.
3. Auto-Negotiation: Communication conditions between 2 PHY transceivers. IP101A LF advertise its
own ability and also detects corresponding operational mode from the other party, eventually both
sides will come to an agreement for their optimized transmission mode.
IP101A LF’s major features included:
1. Flow Control ability
2. LED configuration access
3. Operation modes for both full and half duplex
4. APS (Auto Power Saving) mode
5. Base Line Wander (BLW) compensation
6. Auto MDI/MDIX function
7. Interrupt function
8. Repeater Mode
9. Flexible clock source
Major Functional Block Description
The functional blocks diagram is referred to Figure 1:
1. 4B/5B encoder: 100 Base-X transmissions require converting 4-bit nibble data into 5-bit wide data
code-word format. Transmitting data is packaged by J/K codes at the start of packet and by T/R codes
at the end of packet in the 4B/5B block. When transmit error has occurred during a transmitting
process, the H error code will be sent. The idle code is sent between two packets.
2. 4B/5B Decoder: The decoder performs the 5B/4B decoding from the received code-groups. The 5
bits (5B) data is decoded into four bits nibble data. The decoded 4 bit (4B) data is then forwarded
through MII to the repeater, switch or MAC device. The SSD is then converted into 4B 5 nibbles and
the ESD and IDLE Codes are replaced by 4B 0 nibbles data. The decoded data is driven onto the
corresponding MII port or shared MII port. Receiving an invalid code group will cause PHY to assert
the MII RXER signal.
3. Scrambler/Descrambler: Repetitive patterns exist in 4B/5B encoded data which result in large RF
spectrum peaks and keep the system from being approved by regulatory agencies. The peak in the
radiated signal is reduced significantly by scrambling the transmitted signal. Scrambler adds a
random generator to the data signal output. The resulting signal is with fewer repetitive data patterns.
The scrambled data stream is descrambled at the receiver by adding another random generator to the
output. The receiver’s random generator has the same function as the transmitter’s random generator.
Scrambler operation is dictated by the 100Base-TX and TP_FDDI standards.
4. NRZI/MLT-3(Manchester) Encoder and Decoder: 100Base-TX Transmission requires to encode the
data into NRZ format and again converted into MLT-3 signal, while 10 Base-T will convert into
Manchester form after NRZ coding. This helps to remove the high frequency noise generated by the
twisted pair cables. At receiving end, the coding is reversed from MLT-3 (Manchester) signal back to
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