UCC5614

SLUS349B − DECEMBER 1994 − REVISED APRIL 2005

2

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DESCRIPTION (CONTINUED)

The UCC5614 can be programmed for either a 110-

Ω or 2.5-kΩ termination. The 110-Ω termination is used for

standard SCSI bus lengths and the 2.5-k

Ω termination is typically used in short bus applications. When driving

the TTL compatible DISCNCT pin directly, the 110-

Ω termination is connected when the DISCNCT pin is driven

low, and disconnected when driven high. When the DISCNCT pin is driven through an impedance between

80 k

Ω and 150 kΩ, the terminator is in short bus mode. The 2.5-kΩ termination is connected when the DISCNCT

pin is driven low and disconnected when driven high.

The power amplifier output stage allows the UCC5614 to source full termination current and sink active negation

current when all termination lines are actively negated.

The UCC5614 is pin for pin compatible with Unitrode’s other 9-line SCSI terminators, allowing lower capacitance

and lower voltage upgrades to existing systems. The UCC5614, as with all Unitrode terminators, is completely

hot pluggable and appears as high impedance at the terminating channels with VTRMPWR = 0 V or open.

Internal circuit trimming is utilized, first to trim the 110-

Ω termination impedance to a 7% tolerance, and then most

importantly, to trim the output current to a 4% tolerance, as close to the max SCSI specification as possible,

which maximizes noise margin in fast SCSI operation.

Other features include thermal shutdown and current limit.

This device is offered in low thermal resistance versions of the industry standard 16-pin narrow body SOIC,

16-pin N and 24-pin TSSOP.

ORDERING INFORMATION

TA

PACKAGED DEVICE

TA

SOIC-16 (DP)

{

DIL-16 (N)

TSSOP-24 (PW)

}

0

°C to 70°C

UCC5614DP

UCC5614N

UCC5614PW

†

† The DP package is available taped and reeled in quanities of 2,500. Add TR suffix to device type (e.g. UCC5614DPTR) to order quantities of

2,500 devices per reel.

‡ The PW package is available taped and reeled in quanities of 2,000. Add TR suffix to device type (e.g. UCC5614PWTR) to order quantities of

2,000 devices per reel.

Obsolete Device