DESCRIPTION

The UCC5622 provides 27 lines of active termination for a SCSI (Small
Computer Systems Interface) parallel bus. The SCSI standard recom-
mends active termination at both ends of the cable.

The UCC5622 is ideal for high performance 5V SCSI systems. During dis-
connect the supply current is typically only 100

A, which makes the IC at-

tractive for lower powered systems.

The UCC5622 features a split disconnect allowing the user to control termi-
nation lines 10 to 27 with disconnect one, DISCNCT1, and control terminia-
tion lines 1 to 9 with disconnect two, DISCNCT2.

The UCC5622 is designed with a low channel capacitance of 2.5pF, which
eliminates effects on signal integrity from disconnected terminators at in-
terim points on the bus.

The power amplifier output stage allows the UCC5622 to source full termi-
nation current and sink active negation current when all termination lines
are actively negated.

The UCC5622, as with all Unitrode terminators, is completely hot plugga-
ble and appears as high impedance at the teminating channels with
V

TRMPWR

= 0V or open.

Internal circuit trimming is utilized, first to trim the 110

impedance, and

then most importantly, to trim the output current as close to the maximum
SCSI-3 specification as possible, which maximizes noise margin in FAST-
20 SCSI operation.

(continued)

UCC5622

27 - Line SCSI Terminator With Split Disconnect

BLOCK DIAGRAM

FEATURES

Complies with SCSI, SCSI-2, SCSI-3,
SPI and FAST-20 (Ultra) Standards

2.5pF Channel Capacitance During
Disconnect

100

A Supply Current in Disconnect

Mode

4V To 7V Operation

110

Termination

Completely Meets SCSI Hot Plugging

900mA Sourcing Current for
Termination

+500mA Sinking Current for Active
Negation

Logic Command Disconnects all
Termination Lines

Split Disconnect Controls Lines 1 to 9
and 10 to 27 Separately

Trimmed Impedance to 5%

Current Limit and Thermal Shutdown
Protection

10/98

UDG-96113

Circuit Design Patented

UCC5622

Other features include thermal shutdown and current limit.
This device is offered in low thermal resistance versions
of the industry standard 44 pin wide body QSOP (MWP)
and 48 pin LQFP (FQP). Consult QSOP-44 and LQFP-48
Packaging Diagram for exact dimensions.

DESCRIPTION (cont.)

CONNECTION DIAGRAM

SSOP-44 (Top View)
MWP Package

LQFP-48 (Top View)
MWP Package

ABSOLUTE MAXIMUM RATINGS

TRMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5A
Storage Temperature . . . . . . . . . . . . . . . . . . .

65°C to +150°C

Junction Temperature . . . . . . . . . . . . . . . . . . .

55°C to +150°C

Lead Temperature (Soldering, 10 Sec.). . . . . . . . . . . . . +300°C

Currents are positive into, negative out of the specified termi-
nal. Consult Packaging Section of Databook for thermal limita-
tions and considerations of packages.

ELECTRICAL CHARACTERISTICS

Unless otherwise stated, these specifications apply for T

= 0°C to 70°C,

TRMPWR = 4.75V, DISCNCT1 = DSCNCT2 = 0V, T

= T

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Supply Current Section

TRMPWR Supply Current

All Termination Lines = Open

All Termination Lines = 0.2V

630

650

Power Down Mode

DISCNCT1 = DSCNCT2 = TRMPWR

100

200

UCC5622

ELECTRICAL CHARACTERISTICS

Unless otherwise stated, these specifications apply for T

= 0°C to 70°C,

TRMPWR = 4.75V, DISCNCT1 = DSCNCT2 = 0V, T

= T

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Output Section (Termination Lines)

Termination Impedance

(Note 3)

104.5

110

115.5

Output High Voltage

(Note 1)

2.6

2.8

3.0

Max Output Current

LINE

= 0.2V, T

= 25

22.1

23.3

LINE

= 0.2V

20.7

23.3

LINE

= 0.2V, TRMPWR = 4V, T

= 25

C (Note 1)

LINE

= 0.2V, TRMPWR = 4V (Note 1)

LINE

= 0.5V

22.4

Output Leakage

DISCNCT1 = DISCNCT2 = 2.4V, TRMPWR = 0V to
5.25V

400

Output Capacitance

DISCNCT1 = DISCNCT2 = 2.4V (Note 2)

2.5

Regulator Section

Regulator Output Voltage

2.6

2.8

3.0

Drop Out Voltage

All Termination Lines = 0.2V

0.4

0.8

Short Circuit Current

REG

= 0V

650

900

1300

Sinking Current Capability

REG

= 3.5V

300

500

900

Thermal Shutdown

170

°C

Thermal Shutdown Hysteresis

°C

Disconnect Section

Disconnect Threshold DISCNCT1

Controls Lines 10 to 27

0.8

1.5

2.0

Input Current DISCNCT1

DISCNCT1 = 0V

Disconnect Threshold DISCNCT2

Controls Lines 1 to 9

0.8

1.5

Input Current DISCNCT2

DISCNCT2 = 0V

Note 1:Measuring each termination line while other 26 are low (0.2V).
Note 2:Guaranteed by design. Not 100% tested in production.
Note 3: Tested by measuring I

OUT

with V

OUT

= 0.2V and V

OUT

with no load, then calculate:

Z V

N L

OUT

. .

0 2

2 0

PIN DESCRIPTIONS

DISCNCT1: Disconnect one controls termination lines
10 27. Taking this pin high or leaving it open causes
termination lines 10 - 27 to become high impedence, tak-
ing this pin low allows the channels to provide normal ter-
mination.

DISCNCT2: Disconnect two controls termination lines
1 9. Taking this pin high or leaving it open causes
termination lines 1 - 9 to become high impedence. Taking
this pin low allows the channels to provide normal
terminiation. Taking both disconnect pins high or leaving
them open will put the chip in to sleep mode where it will
be in low-power mode.

GND: Ground reference for the IC.

L1 L27: 110

termination channels.

REG: Output of the internal 2.7V regulator.

TRMPWR: Power for the IC.

IMPORTANT NOTICE

Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.

CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ("CRITICAL
APPLICATIONS"). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO
BE FULLY AT THE CUSTOMER'S RISK.

In order to minimize risks associated with the customer's applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI's publication of information regarding any third
party's products or services does not constitute TI's approval, warranty or endorsement thereof.

1999, Texas Instruments Incorporated

Part Number UCC5622