LXT914 データシートの表示（PDF） - Intel

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LXT914

Flexible Quad Ethernet Repeater

Intel 

Intel® LXT914 Flexible Quad Ethernet Repeater

Table 2.

Inter-Repeater Backplane Signal Descriptions

PLCC PQFP Symbol I/O

Description

Inter-Repeater Backplane Enable. This pin allows individual LXT914

4

94 IRENA I/O repeaters to take control of the Inter-Repeater Backplane (IRB) data bus

(IRDAT). The IRENA bus must be pulled up locally by a 330 Ω resistor.1

5

95

IRDAT

I/O

IRB Data. This pin is used to pass data between multiple repeaters on the

IRB. The IRDAT bus must be pulled up locally by a 330 Ω resistor.1

IRB Driver Enable. The IRDEN pin is used to enable external bus drivers

6

96

IRDEN

O

which may be required in synchronous systems with large backplanes. This

is an active Low signal, maintained for the duration of the data

transmission. IRDEN must be pulled up locally by a 330 Ω resistor.

IRB Collision Flag Sense (IRCFS) and IRB Collision (IRCOL). These two

7

97

IRCFS I/O pins are used for collision signalling between multiple LXT914 devices on

the Inter-Repeater Backplane (IRB). Both the IRCFS bus and the IRCOL

8

98

IRCOL I/O bus must be pulled up globally with 330 Ω resistors. (IRCFS requires a

precision resistor [±1%].)2

NOTES:

1. IRENA and IRDAT can be buffered between boards in multi-board configurations. Where buffering is used,

a 330 Ω pull-up resistor can be used on each signal, on each board. Where no buffering is used, the total

impedance should be no less than 330 Ω.

2. IRCFS and IRCOL cannot be buffered. In multi-board configurations, the total impedance on IRCOL should

be no smaller than 330 Ω. IRCFS should be pulled up only once, by a single 330 Ω, 1% resistor.

Table 3.

Mode Select and Control Signal Descriptions

PLCC PQFP Symbol I/O

Description

Backplane Sync Mode Select. This pin selects the backplane sync mode.

When this pin is left floating an internal pull-up defaults to the

Asynchronous mode (A/SYNC High). In the asynchronous mode 12 or

12

8 A/SYNC I more LXT914s can be connected on the backplane, and an external 10

MHz backplane clock source is not required. When the synchronous mode

is selected (A/SYNC tied Low), 32 or more LXT914s can be connected to

the backplane and an external 10 MHz backplane clock source is required.

Management Mode Select. This pin selects the management mode. When

this pin is left floating, an internal pull-up defaults to the Local management

13

9 LOC/EXT I mode (LOC/EXT High). In the Local mode, setup parameters are

downloaded from an EEPROM during initialization. Once initialized with the

setup parameters, the repeater functions independently.

LED Driver or DTE/MAU Select. At reset, this pin selects the mode of the

28

33

LEDJM/

AUISEL

AUI port. If left floating, an internal pull-down device forces the AUI port to

I/O DTE mode. If pulled High with an external resistor, the port changes to a

MAU, in which case the functions of the LEDJM pin are disabled and the

default LED mode (Refer to Table 7) is not available.

DTE/MAU Select. This pin changes the mode of the AUI port independent

—

30 AUISEL I of the condition at reset. This function is available only in the 100-pin PQFP

package.

17

14

LEDM0 I/O LED Mode 0 & 1 Select. These two pins select one of four possible LED

35

40

modes of operation. The Functional Description section describes the four

LEDM1 I/O modes.

31-Oct-2005

10

Intel® LXT914 Flexible Quad Ethernet Repeater

Order Number: 248989, Revision: 003

Datasheet

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