DS2120 Datasheet, PDF (1/10 Pages) Dallas Semiconductor – Ultra3 LVD SCSI Terminator

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DS2120
Ultra3 LVD SCSI Terminator
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
PIN ASSIGNMENT
VREF 1
R1P 2
R1N 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
DS2120E 28-Pin TSSOP
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
VREF 1
NC 2
NC 3
R1P 4
R1N 5
R2P 6
R2N 7
HS GND 8
HS GND 9
HS GND 10
R3P 11
R3N 12
R4P 13
R4N 14
R5P 15
R5N 16
ISO 17
GND 18
36 TPWR
35 NC
34 LVD
33 NC
32 R9N
31 ^R9P
30 R8N
29 R8P
28 HS GND
27 HS GND
26 HS GND
25 ^R7N
24 R7P
23 R6N
22 R6P
21 DIFF_CAP
20 DIFFSENSE
19 MSTR/SLV
DS2120B 36-Pin SSOP
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.
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.
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