DS21T06

Manufacturer Part NumberDS21T06
DescriptionSCSI Terminator
ManufacturerDallas Semiconducotr
DS21T06 datasheet
 


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FEATURES
Fully compliant with SCSI-1, Fast SCSI and
Ultra SCSI
Functional drop in replacement for the
DS2106
Complimentary part to DS21T07 for wide
SCSI
Provides active termination for 18 signal lines
5% tolerance on termination resistors and
voltage regulator
5% tolerance on termination current
Low power down capacitance of 3 pF
Onboard thermal shutdown circuitry
SCSI bus hot plug compatible
Fully supports actively negated SCSI signals
DESCRIPTION
Fast SCSI and Ultra SCSI require the use of active terminations at both ends of every cable segment in a
SCSI system with single-ended drivers and receivers. Ultra SCSI requires support of active negation and
hot plugging. The DS21T06 is fully compliant with these standards.
The DS21T06 integrates a low dropout regulator and 18 precise switched 110 ohms termination resistors
into a 28-pin 300-mil SOIC package.
Active termination provides greater immunity to voltage drops on the TERMPWR (TERMination
PoWeR) line, enhanced high-level noise immunity, intrinsic TERMPWR decoupling, and very low
quiescent current consumption. One DS21T06 can be used to terminate the Narrow SCSI bus, or a
DS21T07 can be used with a DS21T06 for termination of a Wide SCSI bus.
REFERENCE DOCUMENTS
SCSI-2 (X3.131-1994)
SCSI-3 Parallel Interface (X3T10/855D)
SCSI-3 Fast–20 (X3T10/1071D)
Available from: Global Engineering Documents
15 Inverness Way East
Englewood, CO 80112-5704
Phone: (800) 854-7179,(303) 792-2181
Fax: (303) 792-2192
SCSI Terminator
PIN ASSIGNMENT
PD
1
R1
2
R2
3
R3
4
R4
5
R5
6
HS-GND
7
HS-GND
8
NC
9
R6
10
R7
11
R8
12
R9
13
TPWR
14
DS21T06S 28-Pin SOIC (300-mil)
1 of 6
DS21T06
28
GND
27
R18
26
R17
R16
25
R15
24
R14
23
NC
22
21
HS-GND
NC
20
R13
19
R12
18
R11
17
16
R10
V
15
REF
112099

DS21T06 Summary of contents

  • Page 1

    ... Active termination provides greater immunity to voltage drops on the TERMPWR (TERMination PoWeR) line, enhanced high-level noise immunity, intrinsic TERMPWR decoupling, and very low quiescent current consumption. One DS21T06 can be used to terminate the Narrow SCSI bus DS21T07 can be used with a DS21T06 for termination of a Wide SCSI bus. ...

  • Page 2

    ... Figure 2 details a typical SCSI bus configuration 8-bit data SCSI bus (Narrow SCSI), one DS21T06 is needed for proper termination of the 18 active signal lines. One DS21T06 and one DS21T07 can be used to terminate the 27 active signal lines in a 16- bit data SCSI bus (Wide SCSI). ...

  • Page 3

    ... C2 = 2.2 F tantalum or 4.7 F aluminum C3 = 0.01 F ceramic 2. If the DS21T06 embedded into a peripheral that will act as a target on a SCSI bus recommended that TERMPWR be derived from the SCSI cable, not generated locally. In this configuration power failure occurs in the peripheral, it will not affect the bus. ...

  • Page 4

    ... GND DESCRIPTION Power Down. When tied low, the DS21T06 enters power-down mode. Contains an internal 50 kΩ pull-up. Tie low to deactivate the DS21T06. Tie high or leave open circuited to activate the DS21T06. Signal Termination 1. 110 ohms termination. Connect to SCSI bus signal lines. Heat Sink Ground. Internally connected to the mounting pad. Should be either grounded or electrically isolated from other circuitry ...

  • Page 5

    ... Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. The Dallas Semiconductor DS21T06 is built to the highest quality standards and manufactured for long term reliability. All Dallas Semiconductor devices are made using the same quality materials and manufacturing methods ...

  • Page 6

    NOTES: 1. 4.00V < TERMPWR < 5.50V. 2. 0.0V < signal lines < TERMPWR. 3. All signal lines = 0.0V. 4. All signal lines open. 5. Power-down enabled Guaranteed by design; not production tested 0.2V. ...