ICS1892
10Base-T/100Base-TX Integrated PHYceiver™
TSD
Chapter 7 Functional Blocks
ICS1892 Data Sheet
7.5.13 10Base-T Operation: Auto Polarity Correction
The ICS1892 can sense and then automatically correct a signal polarity that is reversed on its Twisted-Pair
Receiver inputs. A signal polarity reversal occurs if the input signals on the TP_RXP and TP_RXN pins are
crossed or swapped (a problem that can occur during network installation or wiring).
The ICS1892 corrects a reversed signal polarity by examining the signal polarity of the Normal Link Pulses.
Control of this feature is provided by using the 10Base-T Operations Register bit 18.3, the Auto
Polarity-Inhibit bit. When this bit is logic:
• Zero, the ICS1892 automatically senses and corrects a reversed or inverted signal polarity on its
Twisted-Pair Receive pins (TP_RXP and TP_RXN).
• One, the ICS1892 disables this feature.
When the ICS1892 detects a reversed signal polarity on its Twisted-Pair Receive pins and the Auto
Polarity-Inhibit bit is also logic zero, the ICS1892 (1) automatically corrects the data stream and (2) sets the
Polarity Reversed bit (bit 18.14) to logic one, to indicate to the STA that this situation exists. Bit 18.14 is a
latching high (LH) bit. (For more information on latching high and latching low bits, see Section 8.1.4.1,
“Latching High Bits” and Section 8.1.4.2, “Latching Low Bits”.)
Note:
1. The Auto Polarity Correction Function is primarily a 10Base-T operation. However, it is part of the
Twisted-Pair Receiver and is operational during the 100Base-TX auto-negotiation process.
2. For information on the 100Base-TX Auto Polarity Correction, see Section 7.4.7, “100Base-TX
Operation: Auto Polarity Correction (FLP)”.
7.5.14 10Base-T Operation: Isolation Transformer
As per the ISO/IEC specification, the ICS1892 interfaces with a medium through an isolation transformer.
Typically, for each magnetic module there are two isolation transformers: one for the ICS1892 Twisted-Pair
Transmitter and the other for the ICS1892 Twisted-Pair Receiver. For both 10Base-T and 100Base-TX
operations, these isolation transformers provide both physical isolation as well as the means for coupling a
signal between the ICS1892 and the medium.
Note:
1. For information on magnetic modules, see Section 6.6, “Twisted-Pair Interface”.
2. For information on the 10Base-T Isolation Transformer operation, see Section 7.4.8, “100Base-TX
Operation: Isolation Transformer”
ICS1892, Rev. D, 2/26/01
February 26, 2001
© 2000-2001, Integrated Circuit Systems, Inc.
All rights reserved.
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IDT™ / ICS™ 10Base-T/100Base-TX Integrated PHYceiver™
ICS1892
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IDT [ INTEGRATED DEVICE TECHNOLOGY ]
