Key Features

x

SCSI Plug and Play

— Dual active LOW disconnect pins

x

Ultra-Fast response for Fast-20 SCSI

x

35MHz channel bandwidth

x

Sleep-mode current less than 150µA

— Disconnects terminator from lows

x

NO external compensation capacitors

x

Compatible with active negation drivers

x

Compatible with passive and active terminations

x

Approved for use with SCSI 1, 2, 3 and

Ultra SCSI

x

Hot swap compatible

x

Pin-for-pin compatible with LX5225, LX5205

and UC5607

Block Diagrams

–

+

Enable

Logic

Current

Biasing

Circuit

24mA Current

Limiting Circuit

Term Power

DATA OUTPUT

PIN DB (0)

1 of 18 Channels

DISCONNECT 1

DISCONNECT 2

0.4V

2.85V

5225_01.eps

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SCSI T

or

The IMP5225 SCSI terminator is part of IMP's family of high-

performance SCSI terminators, which are designed to deliver true

UltraSCSI performance. The BiCMOS design offers superior perfor-

mance over first generation linear passive and active techniques. IMP's

new architecture employs high-speed adaptive elements for each chan-

nel, thereby providing the fastest response possible — typically 35MHz,

which is 100 times faster than the older linear regulator/terminator

approach. Products using the older regulator/resistor architecture have

bandwidths which are dominated by the reference stabilization output

capacitor and are therefore limited to 500kHz (see further discussion

in the Functional Description section). The IMP architecture eliminates

the output compensation capacitor required in linear regulator/

resistor designs.

The IMP5225 architecture tolerates marginal system designs. A key

improvement offered by the IMP5225 lies in its ability to insure reliable,

error-free communications even in systems which do not adhere to

recommended SCSI hardware design guidelines, such as the use of

improper cable lengths and impedances. Frequently, this situation is not

controlled by the peripheral or host designer.

The IMP5225 has two disconnect pins for SCSI Plug and Play (PnP)

applications. To enter the disconnect mode, the disconnect pins must be

driven LOW thereby disconnecting the IMP5225 from the SCSI bus.

Quiescent current is less than 150

µA when disabled.

Reduced component count is inherent in the IMP5225 architecture.

Traditional termination techniques require large stabilization and

transient protection capacitors of up to 20

µF in value and

size. The IMP5225 architecture does not require these com-

ponents, allowing all the cost savings associated with

inventory, board space, assembly, reliability, and compo-

nent costs.

The IMP5225 is a superior pin-for-pin replacement for the

LX5225, LX5205, UC5607.

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© 2000 IMP, Inc.

408-432-9100/www.impweb.com

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IMP5225

IMP5225