UC5603
9 LINE SCSI ACTIVE TERMINATOR
SLUS195A – MARCH 1997 – REVISED OCTOBER 2000
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Complies with SCSI, SCSI–2 and SPI–2
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Standards
6-pF Channel Capacitance during
Disconnect
100-µA Supply Current in Disconnect Mode
Meets SCSI Hot Plugging
–400-mA Sourcing Current for Termination
+400-mA Sinking Current for Active
Negation Drivers
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Logic Command Disconnects all
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Termination Lines
Trimmed Termination Current to 3%
Trimmed Impedance to 3%
Negative Clamping on all Signal Lines
Current Limit and Thermal Shutdown
Protection
description
The UC5603 provides 9 lines of active termination for a SCSI (Small Computers Systems Interface) parallel bus.
The SCSI standard recommends active termination at both ends of the cable segment.
The UC5603 provides a disconnect feature which, when opened or driven high, will disconnect all terminating
resistors, and disables the regulator; greatly reducing standby power. The output channels remain high
impedance even without Termpwr applied. A low channel capacitance of 6 pF allows units at interim points of
the bus to have little to no effect on the signal integrity.
Functionally the UC5603 is similar to its predecessor, the UC5601 – 18 line Active Terminator. Several electrical
enhancements were incorporated in the UC5603, such as a sink/source regulator output stage to accommodate
all signal lines at 5 V, while the regulator remains at its nominal value, reduced channel capacitance to 6 pF
typical, and as with the UC5601, custom power packages are utilized to allow normal operation at full power
conditions (1.2 watts).
functional block diagram
UDG-94049
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PRODUCTION DATA information is current as of publication date.
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