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090199

FEATURES

Fully compliant with Ultra2, Ultra3, and

Ultra 160/m SCSI

Provides Multimode Low Voltage

Differential/Single-Ended (LVD/SE)

termination for 9 signal line pairs

Auto-selection of LVD or SE termination

5% tolerance on SE and LVD termination

resistance

Low power down capacitance of 3 pF

Onboard thermal shutdown circuitry

SCSI bus hot plug compatible

Fully supports actively negated SE SCSI

signals

PIN ASSIGNMENT

DESCRIPTION

The DS2117M Ultra3 LVD/SE SCSI Terminator is both a Low Voltage Differential (LVD) and Single-

Ended (SE) terminator. The multimode operation enables the designer to implement LVD in current

products while allowing the end-user SE backward compatibility with legacy devices. If the device is

connected in an LVD-only bus, the DS2117M will use LVD termination. If any SE devices are connected

to the bus, the DS2117M will use SE termination. This is accomplished automatically inside the part by

sensing the voltage on the SCSI bus DIFFSENS line.

For the LVD termination, the DS2117M integrates two current sources with nine precision resistor

strings. For the SE termination, one regulator and nine precision 110-ohm resistors are used. Three

DS2117M terminators are needed for a wide SCSI bus.

DS2117M

Ultra3 LVD/SE SCSI Terminator

www.dalsemi.com

32

35

34

33

31

30

29

28

27

26

25

24

LVD

SE

R9N

R8N

R8P

HS GND

HS GND

HS GND

R7N

R7P

R6N

R9P

NC

R1P

R1N

R2N

HS GND

HS GND

R3P

R3N

R4P

R4N

R2P

DS2117MB 36-Pin SSOP

36

23

VREF

NC

TPWR

HVD

HS GND

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

22

21

20

19

R5P

R5N

ISO

GND

DIFF_CAP

DIFFSENSE

MSTR/SLV

R6P