Complies with SCSI, SCSI-2

and SPI-2 Standards

5pF Channel Capacitance

during Disconnect

Meets SCSI Hot Plugging

400mA Sourcing Current for

Termination

+100mA Sinking Current for

Active Negation

1V Dropout Voltage Regulator

Logic High Command

Disconnects all Termination
Lines

100

A Supply Current in

Disconnect Mode

Trimmed Termination Current

to 5%

Trimmed Impedance to 5%

Low Thermal Resistance

Surface Mount Packages

The UC5612 provides 9 lines of active termination for a SCSI (Small Computer
Systems Interface) parallel bus. The SCSI standard recommends active termi-
nation at both ends of the cable segment.

The only functional differences between the UC5603 and UC5612 is the ab-
sence of the negative clamps on the output lines. Parametrically, the UC5612
has a 5% tolerance on impedance and current compared to a 3% tolerance on
the UC5603. Custom power packages are utilized to allow normal operation at
full power (2 Watts).

The UC5612 provides a disconnect feature which, when opened or driven high,
disconnects all terminating resistors, disables the regulator and greatly reduces
standby power consumption. The output channels remain high impedance even
without Termpwr applied. A low channel capacitance of 5pF allows interim
points of the bus to have little to no effect on the signal integrity.

Internal circuit trimming is utilized, first to trim the impedance to a 5% tolerance,
and then most importantly, to trim the output current to a 5% tolerance, as close
to the maximum SCSI specification as possible. This maximizes the noise mar-
gin in fast SCSI operation. Other features include thermal shutdown and cur-
rent limit.

This device is offered in low thermal resistance versions of the industry stand-
ard 16 pin narrow body SOIC, 16 pin ZIP (zig-zag in line package) and 24 pin
TSSOP.

UC5612

9-Line Low Capacitance SCSI Active Terminator

FEATURES DESCRIPTION

BLOCK DIAGRAM

Circuit Design Patented

3/97

UDG-94133

ABSOLUTE MAXIMUM RATINGS

Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6A
Storage Temperature . . . . . . . . . . . . . . . . . . .

65°C to +150°C

Operating Temperature . . . . . . . . . . . . . . . . .

55°C to +150°C

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

RECOMMENDED OPERATING CONDITIONS

Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 3.8V to 5.25V
Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V
Disconnect Input Voltage . . . . . . . . . . . . . . . . . . 0V to Termpwr

CONNECTION DIAGRAMS

DIL-16 (Top View)
N or J Package

UC5612

* DP package pin 5 serves as signal ground; pins 4, 12, 13
serve as heatsink/ground.

* PWP package pin 9 serves as signal ground; pins 5, 6, 7, 8,
17, 18, 19, and 20 serve as heatsink/ground.

ZIP-16 (Top View)
Z Package

SOIC-16 (Top View)
DP Package

TSSOP-24 (Top View)
PWP Package

Note: Drawings are not to scale.

Unless otherwise specified all voltages are with respect to
Ground. Currents are positive into, negative out of the speci-
fied terminal.
Consult Packaging Section of Unitrode Integrated Circuits dat-
abook for thermal limitations and considerations of packages.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

Supply Current Section

Termpwr Supply Current

All termination lines = Open

All termination lines = 0.5V

200

225

Power Down Mode

DISCNCT = Open

100

150

Output Section (Termination Lines)

Terminator Impedance

LINE

= -5mA to -15mA

104.5

110

115.5

Ohms

Output High Voltage

2.65

2.9

3.1

Max Output Current

LINE

= 0.5V

= 25

-20.3

-21.5

-22.4

0°C < T

< 70°C

-19.8

-21.5

-22.4

Max Output Current

LINE

= 0.5V, TRMPWR = 4V (Note 1)

= 25

-19.5

-21.5

-22.4

0°C < T

< 70°C

-19.0

-21.5

-22.4

LINE

= 0.2V, TRMPWR = 4V to 5.25V

0°C < T

< 70°C

-21.6

-24.0

-25.4

Output Leakage

DISCNCT = 4V
TRMPWR = 0V to 5.25V

REG = 0V

LINE

= 0 to 4V

400

LINE

= 5.25V

100

REG = Open V

LINE

= 0V to 5.25V

400

Output Capacitance

DISCNCT = Open (Note 2) (DP Package)

Regulator Section

Regulator Output Voltage

2.7

2.9

3.1

All Termination Lines = 4V

2.7

2.9

3.1

Line Regulation

TRMPWR = 4V to 6V

Drop Out Voltage

All Termination Lines = 0.5V

1.0

1.2

Short Circuit Current

REG = 0V

-200

-400

-600

Sinking Current Capability

REG = 3.5V

100

400

Thermal Shutdown

170

°C

Thermal Shutdown Hysteresis

°C

Disconnect Section

Disconnect Threshold

1.1

1.4

1.7

Input Current

DISCNCT = 0V

-10

-20

ELECTRICAL CHARACTERISTICS

Unless otherwise stated, these specifications apply for T

= 0°C to 70°C.

TRMPWR = 4.75V, DISCNCT = 0V, T

= T

UC5612

Note 1: Measuring each termination line while other 8 are low.
Note 2: Guaranteed by design. Not 100% tested in production.

Figure 1: Typical SCSI Bus Configurations Utilizing 2 UC5612 Devices

APPLICATION INFORMATION

UDG-94134

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

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: UC5612

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: UC5612