DP83959 datasheet(9/38 Pages) NSC

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4.0

Pin Descriptions (Continued)

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4.4

INTER-LERIC BUS INTERFACE

/PART0

O (14mA

max.)

Partition LED 0: Partition LED output for the AUI port. Active low.

/GCOL

O (14mA

max.)

Global Collision LED: Global collision status LED output. Indicates collision

activity on any port. Active low. This output will be asserted low until the start

of the next network event or for a maximum of 30ms (nominal value).

/GACT

O (14mA

max.)

Global Activity LED: Global Activity LED output. Indicates receive activity

(carrier sense active) on any port. Active low. This output will be asserted low

until the start of the next network event or for a maximum of 30ms (nominal

value).

Signal Name

Type

Pin #

Description

Signal Name

Type

Pin #

Description

/ACKI

Acknowledge Input: to the network ports' arbitration chain. If the Inter-LERIC

bus is not being used or if this LERIC8 is at the top of the /ACKI - /ACKO chain

or is the only repeater chip in the system, this pin should be connected to VCC

either directly or via a pull-up resistor (

≈ 4.7 kΩ). Otherwise, this input should

be driven from the previous LERIC8's /ACKO output.

/ACKO

Acknowledge Output: from the network ports' arbitration chain, connected to

the /ACKI of the next repeater chip in the /ACKI - /ACKO chain. If this LERIC8

is not chained to any other repeater chips, this pin should be left unconnected.

IRD

I/O

Inter-LERIC Data: When asserted as an output this signal provides a serial

data stream in NRZ format. The signal is asserted by a LERIC8 when it is

receiving data from one of its network segments. The default condition of this

signal is to be an input. In this state it may be driven by other devices on the

Inter-LERIC bus. If the Inter-LERIC bus is not being used, this pin should be

left unconnected (it has an internal pull-up resistor of 14 k

Ω) or pulled up to

VCC via an external resistor.

/IRE

I/O

Inter-LERIC Enable: When asserted as an output this signal provides an

activity framing enable for the serial data stream. The signal is asserted by a

LERIC8 when it is receiving data from one of its network segments. The

default condition of this signal is to be an input. In this state it may be driven by

other devices on the Inter-LERIC bus. If the Inter-LERIC bus is not being

used, this pin should be left unconnected (it has an internal pull-up resistor of

14 k

Ω) or pulled up to V

CC via an external resistor. If the Inter-LERIC bus is to

be used, this signal should have an external 680

Ω pull-up resistor to ensure

fast de-assertion.

IRC

I/O

Inter-LERIC Clock: When asserted as an output this signal provides a clock

signal for the serial data stream. Data (IRD) is changed on the falling edge of

the clock. The signal is asserted by a LERIC8 when it is receiving data from

one of its network segments. The default condition of this signal is to be an

input. When an input, IRD is sampled on the rising edge of the clock. In this

state it may be driven by other devices on the Inter-LERIC bus. If the

Inter-LERIC bus is not being used, this pin should be left unconnected (it has

an internal pull-up resistor of 14 k

Ω) or pulled up to V

CC via an external

resistor.

/COLN

I/O

Collision on Port N: This denotes that a collision is occurring on the port

receiving the data packet (Port N). The default condition of this signal is to be

an input. In this state it may be driven by other devices on the Inter-LERIC

bus. If the Inter-LERIC bus is not being used, this pin should be left

unconnected (it has an internal pull-up resistor of 3.5 k

Ω) or pulled up to V

via an external resistor. If the Inter-LERIC bus is to be used, this signal should

have an external 680

Ω pull-up resistor to ensure fast de-assertion.

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