DS2120
Ultra3 LVD SCSI Terminator
www.maxim-ic.com
FEATURES
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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
R1P
R1N
R2P
R2N
HS GND
R3P
R3N
R4P
R4N
R5P
R5N
ISO
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
TPWR
TPWR
R9N
R9P
R8N
R8P
HS GND
R7N
R7P
R6N
R6P
DIFF_CAP
DIFFSENSE
MSTR/SLV
DS2120E 28-Pin TSSOP
VREF
NC
NC
R1P
R1N
R2P
R2N
HS GND
HS GND
HS GND
R3P
R3N
R4P
R4N
R5P
R5N
ISO
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
TPWR
NC
LVD
NC
R9N
R9P
R8N
R8P
HS GND
HS GND
HS GND
R7N
R7P
R6N
R6P
DIFF_CAP
DIFFSENSE
MSTR/SLV
APPLICATIONS
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Raid Systems
SCSI Host Bus Adapter Cards (HBA)
Servers
SCSI Cables
Network Attached Storage (NAS)
Storage Area Networks (SANs)
ORDERING INFORMATION
DS2120E
DS2120B
28-Pin TSSOP
36-Pin SSOP
0°C to +70°C
0°C to +70°C
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:
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042602
DALLAS [ DALLAS SEMICONDUCTOR ]
