LX5112 データシートの表示（PDF） - Microsemi Corporation

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LX5112

ULTRA 9 - CHANNEL SCSI TERMINATOR

Microsemi Corporation 

LX5111/5112

PRODUCT DATABOOK 1996/1997

ULTRA 9-CHANNEL SCSI TERMINATOR

PRODUCTION DATA SHEET

TERM POWER

BLOCK DIAGRAM

THERMAL

LIMITING

CIRCUIT

CURRENT

BIASING

CIRCUIT

24mA CURRENT

LIMITING CIRCUIT

UltraMAX

DATA OUTPUT

PIN DB(0)

DISCONNECT (5111)

DISCONNECT (5112)

1.4V

2.85V

1 OF 9 CHANNELS

FUNCTIONAL DESCRIPTION

Cable transmission theory suggests to optimize signal speed 2.85V on deassertion. In order to disable the device, the

and quality, the termination should act both as an ideal voltage DISCONNECT pin (DISCONNECT pin for the LX5112) must be

reference when the line is released (deasserted) and as an ideal driven logic Low (logic High for the LX5112). This mode of

current source when the line is active (asserted). Common operation places the devices in a sleep state where a meager

active terminators, which consist of Linear Regulators in series 275µA of quiescent current is consumed. Additionally, all outputs

with resistors (typically 110Ω), are

a compromise. As the line voltage

POWER UP / POWER DOWN FUNCTION TABLE

are in a Hi-Z (impedance) state.

Sleep mode can be used for power

increases, the amount of current

decreases linearly by the equation

V = I * R. The LX5111/5112, with

LX5111 LX5112

DISCONNECT DISCONNECT

Outputs

Quiescent

Current

conservation or to completely elimi-

nate the terminator from the SCSI

chain. In the second case, termi-

their unique new architecture ap-

plies the maximum amount of

current regardless of line voltage

until the termination high threshold

H

L

Open

L

H

Open

Enabled

HI Z

HI Z

6mA

275µA

275µA

nation node capacitance is impor-

tant to consider. The terminators

will appear as a parasitic distributed

capacitance on the line, which can

(2.85V) is reached.

detract from bus performance. For

Acting as a near ideal line terminators, the LX5111/5112 this reason, the LX5111/5112 have been optimized to have only

closely reproduce the optimum case when the devices are 3pF of capacitance per output in the sleep state.

enabled. To enable the device the DISCONNECT pin

An additional feature of the LX5111/5112 IC's are their

(DISCONNECT pin for the LX5112) must be pulled logic High compatibility with active negation drivers. These devices handle

(logic Low for the LX5112). During this mode of operation, up to 60mA of sink current for drivers which exceed the 2.85V

quiescent current is 6mA and the devices will respond to line output high.

demands by delivering 24mA on assertion, and by imposing

UltraMAX is a trademark of Linfinity Microelectronics Inc.

PRODUCTION DATA - Information contained in this document is proprietary to Linfinity, and is current as of publication date. This document

may not be modified in any way without the express written consent of Linfinity. Product processing does not necessarily include testing of

all parameters. Linfinity reserves the right to change the configuration and performance of the product and to discontinue product at any time.

4

Copyright © 1997

Rev. 1.1 12/97

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