鈥?/div>
Complies with SCSI, SCSI-2
Standards
10pF Channel Capacitance During
Disconnect
Active Termination for 18 Lines
Logic Command Disconnects all
Termination Lines
Low Supply Current in Disconnect
Mode
Trimmed Regulator for Accurate
Termination Current
Current Limit and Thermal
Shutdown Protection
110 Ohm Termination
Meets SCSI Hot Plugging
DESCRIPTION
The UC5602 is a pin compatible version of its predecessor, the UC5601,
and is targeted for high volume applications which require active termina-
tion, but not the high performance of the UC5601. The major differences
are relaxed output current and termination tolerances, and the absence of
low side clamps.
The UC5602 provides 18 lines of active termination for a SCSI (Small
Computer Systems Interface) parallel bus. The SCSI-2 standard recom-
mends active termination at both ends of the cable segment, and SCSI-3
will make it a requirement.
The UC5602 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 imped-
ance even without Termpwr applied.
Internal circuit trimming is utilized, first to trim the impedance to a 7% toler-
ance; and then most importantly, to trim the output current 7% tolerance,
as close to the max SCSI as possible, which maximizes noise margin in
fast SCSI operation.
Other features include thermal shutdown, current limit, and 40mA of active
negation sink current capability.
This device is offered in low thermal resistance versions of the industry
standard 28 pin wide body SOIC and PLCC, as well as a 24 pin DIL plastic
package.
BLOCK DIAGRAM
UDG-94052
10/94
Circuit Design Patented
1
2
3
4
5
6
