NS32492A

Features:

· Compatible with Ethernet II, IEEE 802.3 10Base5 and 10Base2 (Cheapernet)
· Integrates all transceiver electronics except signal & power isolation
· Innovative design minimizes external component count
· Jabber timer function integrated on chip
· Externally selectable CD Heartbeat allows operation with IEEE 802.3 compatible repeaters
· Precision circuitry implements receive mode collision detection
· Squelch circuitry at all inputs rejects noise
· Designed for rigorous reliability requirements of IEEE 802.3
· Standard Outline 16-pin DIP uses a special leadframe that significantly reduces the operating die temperature


Description

The DP8392A Coaxial Transceiver Interface (CTI) is a coaxial cable line driver/receiver for Ethernet/Thin Ethernet (Cheapernet) type local area networks. The CTI is connected between the coaxial cable and the Data Terminal Equipment (DTE). In Ethernet applications the transceiver is usually mounted within a dedicated enclosure and is connected to the DTE via a transceiver cable. In Cheapernet applications, the CTI is typically located within the DTE and connects to the DTE through isolation transformers only. The CTI consists of a Receiver, Transmitter, Collision Detector, and a Jabber Timer. The Transmitter connects directly to a 50 ohm coaxial cable where it is used to drive the coax when transmitting. During transmission, a jabber timer is initiated to disable the CTI transmitter in the event of a longer than legal length data packet. Collision Detection circuitry monitors the signals on the coax to determine the presence of colliding packets and signals the DTE in the event of a collision.

The DP8392A CTI is part of a three chip set that implements the complete IEEE 802.3 compatible network node electronics as shown below. The other two chips are the DP8391 Serial Network Interface (SNI) and the DP8390 Network Interface Controller (NIC).

The DP8392A SNI provides the Manchester encoding and decoding functions; whereas the NIC handles the Media Access Protocol and the buffer management tasks. Isolation between the CTI and the SNI is an IEEE 802.3 requirement that can be easily satisfied on signal lines using a set of pulse transformers that come in a standard DIP. However, the power isolation for the CTI is done by DC-to-DC conversion through a power transformer.