DS2119M Datasheet, PDF (1/9 Pages) Dallas Semiconductor – Ultra3 LVD/SE SCSI Terminator

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DS2119M
Ultra3 LVD/SE SCSI Terminator
FEATURES
Fully compliant with SCSI SPI-2, SPI-3,
SPI-4, Ultra160, and Ultra320
Provides multimode low-voltage
differential/single-ended (LVD/SE)
termination for nine signal-line pairs
Auto-selection of LVD or SE termination
5% tolerance on SE and LVD termination
resistance
Low power-down capacitance of 3pF
Onboard thermal-shutdown circuitry
SCSI-bus hot-plug compatible
Fully supports actively negated SE SCSI
signals
PIN ASSIGNMENT
VREF ¹
RIP 2
RIN 3
R2P 4
R2N 5
HS GND 6
R3P 7
R3N 8
R4P 9
R4N 10
R5P 11
R5N 12
ISO 13
GND 14
28 TPWR
27 TPWR
26 R9N
25 R9P
24 R8N
23 R8P
22 HS GND
21 R7N
20 R7P
19 R6N
18 R6P
17 DIFF_CAP
16 DIFFSENSE
15 MSTR/SLV
DS2119ME 28-Pin TSSOP
DESCRIPTION
The DS2119M 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 DS2119M will use LVD termination. If any SE devices are connected
to the bus, the DS2119M 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 DS2119M integrates two current sources with nine precision resistor
strings. For the SE termination, one regulator and nine precision 110Ω resistors are used. Three
DS2119M terminators are needed for a wide SCSI bus.
REFERENCE DOCUMENTS
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface (SPI) Project: 0855-M, 1995
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface 2 (SPI-2) Project: 1142-M, 1998
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface 3 (SPI-3) Project: 1302-D, 1999
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface 4 (SPI-4) Project: 1365-D, 200x
Available From:
American National Standards Institute (ANSI) Phone: [phone]
Global Engineering Documents 15 Inverness Way East; Englewood, CO 80112 Phone: [phone]
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