NS32491A

Features:

Compatible with Ethernet II IEEE 8023 10Base5 10Base2 and 10Base-T
10 Mbs Manchester encodingdecoding with receive clock recovery
Patented digital phase locked loop (DPLL) decoder requires no precision external components
Decodes Manchester data with up to ±18 ns of jitter
Loopback capability for diagnostics
Externally selectable half or full step modes of operation at transmit output
Squelch circuits at the receive and collision inputs reject noise
High voltage protection at transceiver interface (16V)
TTLMOS compatible controller interface
Connects directly to the transceiver (AUI) cable


Specifications

SupplyVoltage(V_CC)...............................................................................7V
InputVoltage(T_TL).......................................................................... 0to55V
InputVoltage(differential)....................................................... -5.5to +16V
OutputVoltage(differential)............................................................ 0to16V
OutputCurrent(differential).............................................................- 40mA
StorageTemperature ..............................................................-65 to150
LeadTemperature(soldering10sec) ..................................................300
PackagePowerRatingforDIPat25 ..................................................2.95W
     (PC Board Mounted)
     Derate Linearly at the rate of 238 mW/
PackagePowerRatingforPCCat25.................................................1.92W
     Derate Linearly at the rate of 154 mW/
For actual power dissipation of the device please refer to
Section 70
ESDrating....................................................................................... 2000V


Description

The DP8391A Serial Network Interface (SNI) provides the Manchester data encoding and decoding functions for IEEE 8023 EthernetCheapernet type local area networks The SNI interfaces the DP8390 Network Interface Controller (NIC) to the Ethernet transceiver cable When transmitting the SNI converts non-return-to-zero (NRZ) data from the controller and clock pulses into Manchester encoding and sends the converted data differentially to the transceiver The opposite process occurs on the receive path where a digital phase-locked loop decodes 10 Mbits signals with as much as ±18 ns of jitter

The DP8391A SNI is a functionally complete Manchester encoderdecoder including ECL like balanced driver and re- ceivers on board crystal oscillator collision signal translator and a diagnostic loopback circuit

The DP8391A SNI is part of a three chip set that implements the complete IEEE compatible network node electronics as shownbelow The other two chips are the DP8392 Coax Transceiver Interface (CTI) and the DP8390 Network Interface Controller (NIC)

DP8391A Incorporated into the CTI are the transceiver collision and jabber functions The Media Access Protocol and the buffer management tasks are performed by the NIC There is an isolation requirement on signal and power lines between the CTI and the SNI This is usually accomplished by using a set of miniature pulse transformers that come in a 16-pin plastic DIP for signal lines Power isolation however is done by using a DC to DC converter