DS21T07
SCSI Terminator
Overview
- Fully compliant with SCSI-1, Fast, and Ultra SCSI standards
- Backward-compatible with DS2107 and DS2107A
- Provides active signal termination for 9 lines
- Handles actively negated SCSI signals
- Laser-trimmed, precision 110-ohm resistors with 2% tolerance
- 2% tolerance on voltage regulator
- Low drop-out voltage
- Low standby current consumption of 100µA
- Power-down mode with resistors isolated from bus
- SCSI bus hot-plug compatible
- Onboard thermal shutdown circuitry
- Operating range:
- 0°C to +70°C
- 4.0V to 5.5V
The DS21T07 is backward-compatible with the DS2107, DS2107A, and DS21S07 providing precision resistance values for SCSI-1, Fast, and Ultra SCSI with 2% tolerance on the resistors and voltage regulator.
The DS21T07 actively terminates cable segments in SCSI systems carrying nine single-ended drivers and receivers. In an 8-bit wide SCSI arrangement, two DS21T07s connected at each end of the SCSI cable can terminate 18 active signal lines. A 16-bit wide SCSI arrangement requires three DS21T07s at each end to terminate 27 active signal lines.
SCSI termination is used wherever data must be transmitted without voltage drops caused by signal reflection at the parallel bus termination point, which is often significant in multidropped systems.
All Dallas terminators feature power-down mode with extremely low-quiescent consumption. Different SCSI terminators are available to match every existing SCSI protocol and to address different design concerns, such as price, board space, and voltage differential.
The DS21T07 gives the end user more margin for configuration because it allows maximum current into the SCSI bus. Where board space is a problem it’s available in a TSSOP package.
Documentation
Data Sheet 1
This is the most up-to-date revision of the Data Sheet.
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