UCC5611_10 Datasheet, PDF (1/6 Pages) Texas Instruments – 18-LINE 3-5VOLT SCSI ACTIVE TERMINATOR REVERSE DISCONNECT

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D Complies with SPI-2 and SPI-3 Standards
D 2.75-V to 7-V Operation
D 1.8-pF Channel Capacitance during
Disconnect
D 1-µA Supply Current in Disconnect Mode
D 110-Ω/2.5-k Programmable Termination
D Completely Meets SCSI Hot Plugging
UCC5611
18ĆLINE 3-5 VOLT SCSI ACTIVE TERMINATOR,
REVERSE DISCONNECT
SLUS348A − MARCH 1997 − REVISED NOVEMBER 2000
D −650-mA Sourcing Current for Termination
D +400-mA Sinking Current for Active
Negation Drivers
D Trimmed Termination Current to 4%
D Trimmed Impedance to 7%
D Current Limit and Thermal Shutdown
Protection
description
The UCC5611 provides 18 lines of active termination for a SCSI (Small Computer Systems Interface) parallel
bus. The SCSI standard recommends active termination at both ends of the cable segment.
The UCC5611 is ideal for high performance 3.3-V SCSI systems. The key features contributing to such
low-operating voltage are the 0.1-V drop-out regulator and the 2.75-V reference. During disconnect the supply
current is typically only 1 µA, which makes the IC attractive for battery powered systems.
The UCC5611 is designed with an ultra-low channel capacitance of 1.8 pF, which eliminates effects on signal
integrity from disconnected terminators at interim points on the bus.
The UCC5611 can be programmed for either a 110-Ω or 2.5-kΩ termination. The 110-Ω termination is used for
standard SCSI bus lengths and the 2.5-kΩ termination is typically used in short bus applications. When driving
the TTL compatible DISCNCT pin directly, the 110-Ω termination is connected when the DISCNCT pin is driven
high, and disconnected when low. When the DISCNCT pin is driven through an impedance between 80 kΩ and
150 kΩ, the 2.5-kΩ termination is connected when the DISCNCT pin is driven high, and disconnected when
driven low.
block diagram
UDG-94131-1
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
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