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042602
Note:
Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple
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
R2P
VREF
NC
R2N
HS GND
HS GND
R3P
R3N
R4P
R4N
R5P
R5N
ISO
GND
HS GND
32
31
30
29
28
27
26
25
24
23
22
21
20
19
35
34
33
36
LVD
NC
R9N
R9P
R8N
R8P
HS GND
HS GND
HS GND
R7N
R7P
R6N
R6P
TPWR
NC
DIFF_CAP
DIFFSENSE
MSTR/SLV
DS2120B 36-Pin
SSOP
VREF
R1P
R1N
R2P
HS GND
R3P
R3N
R4P
R4N
R5P
R5N
ISO
GND
R2N
HS GND
R7N
R7P
R6N
R6P
TPWR
R9N
R9P
DIFF_CAP
DIFFSENSE
MSTR/SLV
R8N
R8P
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