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UCC561

DESCRIPTION

The UCC561 LVD Regulator set is designed to provide the correct refer-

ences voltages and bias currents for LVD termination resistor networks

(475 , 121

and 475 ). The device also provides a 1.3V output for Diff

Sense signaling. With the proper resistor network, the UCC561 solution will

meet the common mode bias impedance, differential bias, and termination

impedance requirements of SPI-2 (Ultra2) and SPI-3 (Ultra3).

This device incorporates into a single monolith, two sink/source reference

voltage regulators, a 1.3V buffered output and protection features. The pro-

tection features include thermal shut down and active current limiting cir-

cuitry. The UCC561 is offered in 16-pin SOIC(DP) package.

Low Voltage Differential SCSI (LVD) 27 Line Regulator Set

FEATURES

SCSI SPI-2 LVD SCSI 27 Line Low

Voltage Differential Regulator

2.7V to 5.25V Operation

Integrated Regulator Set for LVD

SCSI

Differential Failsafe Bias

SLUS413 - MAY 1999

2

DIFSENS

3

TRMPWR

4

PGND

REF 0.75V

7

1.3V +/– 0.1V

REF 1.3V

REF 1.75V

1.75V +/–50mV

200mA SOURCE/SINK

REG1

6

0.75V +/–50mV

200mA SOURCE/SINK

SOURCE/SINK REGULATOR

REG2

2.7V < 5.25V

BLOCK DIAGRAM

UDG-98093

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2

UCC561

SOIC-16 (TOP VIEW)

DP Packages

ABSOLUTE MAXIMUM RATINGS

TERMPWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6V

Package Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2W

Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C

Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°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.

RECOMMENDED OPERATING CONDITIONS

TERMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.25V

N/C

N/C

N/C

HSGND

HSGND

N/C

N/C

N/C

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

TERMPWR

N/C

N/C

REG1

DIFSENS

REG2

HSPGND

HSGND

CONNECTION DIAGRAMS

ELECTRICAL CHARACTERISTICS:

Unless otherwise specified these specifications apply for TA = 0°C to 70°C,

TERMPWR = 3.3V.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNITS

TERMPWR Supply Current Section

TERMPWR Supply Current

No Load

40.0

mA

TERMPWR Voltage

2.7

5.25

V

Regulator Section

1.75 Volt Regulator

REG1 (

±

125mA)

1.7

1.75

1.8

V

1.3 Volt Regulator

DIFSENS , No Load

1.2

1.3

1.4

V

0.75 Volt Regulator

REG2 (

±

125mA)

0.7

0.75

0.8

V

1.75 Volt Regulator Source Current

V

O

= 1.25

–200

mA

1.75 Volt Regulator Sink Current

V

O

= 2.25

200

mA

1.75 Volt Sink Current Limit

700

mA

1.75 Volt Source Current Limit

–700

mA

1.3 Volt Regulator Source Current

DIFSENS, GND

–5

–15

mA

1.3 Volt Regulator Sink Current

DIFSENS, 2.4V

50

200

µ

A

0.75 Volt Regulator Source Current

V

O

= 0.25

–200

mA

0.75 Volt Regulator Sink Current

V

O

= 1.25

200

mA

0.75 Source Current Limit

700

mA

0.75 Sink Current Limit

–700

mA

Note 1: Guaranted by design. Not 100% tested in production.

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3

UCC561

L1+

L27–

L27+

SOURCE/SINK REGULATOR

REF

1.3V

7

DIFSENS

DIFSENS: SOURCE ONLY

FROM TERMPWR

2

TERMPWR

4

PGND

L1–

1.3V ± 0.1V

121 1%

121 1%

6

REF

1.75V

1.75V ± –50mV

200mA SOURCE/SINK

4.7

µ

F

REG1

3

REG2

SOURCE/SINK REGULATOR

REF

0.75V

0.75V ± –50mV

200mA SOURCE/SINK

4.7

µ

F

DIFSENS

475 1%

475 1%

475 1%

475 1%

4.7

µ

F

TERMPWR

2.7V TO 5.25V

APPLICATION INFORMATION

Figure 1. LVD SCSI discrete resistor stack.

UDG-98096

Table I. Resistor stack vs. standard.

Outputs

Specification

107.3

Diff

100

to 110

112.9mV Diff Bias

100mV to 125mV

237

Common Mode

100

to 300

1.25V Common Mode

1.2V to 1.30V

Application Note: The resistor stack with the 1.75V and 0.75V

reference will give the correct differential impedance, bias volt-

age, common mode differential impedance and common mode

voltage as show in Table 1.

UNITRODE CORPORATION

7 CONTINENTAL BLVD. • MERRIMACK, NH  03054

TEL. (603) 424-2410 • FAX (603) 424-3460

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accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent

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Copyright 

©

 1999, Texas Instruments Incorporated