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042602

Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple

revisions of any device may be simultaneously available through various sales channels. For information about device

errata, click here: http://dbserv.maxim-ic.com/errata.cfm.

FEATURES

§ Fully compliant with Ultra3, Ultra160,

Ultra320, and Ultra2 (LVD only) SCSI

§ Provides low-voltage differential (LVD)

termination for nine signal line pairs

§ Zero-temperature coefficient-termination

resistors

§ Auto-select of LVD termination

§ 5% tolerance on LVD termination resistance

§ Low power-down capacitance of 3pF

§ Built-in mode change filter/delay

§ On-board thermal-shutdown circuitry

§ SCSI bus hot-plug compatible

APPLICATIONS

§ Raid Systems

§ SCSI Host Bus Adapter Cards (HBA)

§ Servers

§ SCSI Cables

§ Network Attached Storage (NAS)

§ Storage Area Networks (SANs)

ORDERING INFORMATION

DS2120E

28-Pin TSSOP

0°C to +70°C

DS2120B

36-Pin SSOP

0°C to +70°C

DESCRIPTION

The DS2120 Ultra3 LVD SCSI terminator is a low-voltage differential (LVD) terminator. If the device is

connected in an LVD-only bus, the DS2120 uses LVD termination. If any single-ended (SE) or high-

voltage differential (HVD) devices are connected to the bus, the DS2120 disconnects from the bus. This

is accomplished inside the part automatically by sensing the voltage on the SCSI bus DIFFSENS line.

For the LVD termination, the DS2120 integrates two current sources with nine precision resistor strings.

Three DS2120 terminators are needed for a wide SCSI bus.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

NC

R1P

R1N

VREF

NC

R2N

HS GND

HS GND

R3P

R3N

R4P

R4N

R2P

HS GND

R5P

R5N

ISO

GND

32

35

34

33

31

30

29

28

27

26

25

24

36

23

22

21

20

19

LVD

NC

R9N

R8N

R8P

HS GND

HS GND

HS GND

R7N

R7P

R6N

R9P

TPWR

NC

DIFF_CAP

DIFFSENSE

MSTR/SLV

R6P

DS2120B 36-Pin SSOP

VREF

HS GND

R3P

R3N

R4P

R4N

R5P

R5N

ISO

GND

R1P

R1N

R2N

R2P

HS GND

R7N

R7P

R6N

TPWR

DIFF_CAP

DIFFSENSE

MSTR/SLV

R6P

R9N

R8N

R8P

R9P

TPWR

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

28

27

26

25

24

23

22

21

20

19

DS2120E 28-Pin TSSOP

DS2120

Ultra3 LVD SCSI Terminator

www.maxim-ic.com

PIN ASSIGNMENT