UNITRODE UC5604 Technical data

9-Line Low Capacitance SCSI Active Terminator

FEATURES DESCRIPTION

• Complies with SCSI, SCSI-2
Standards

• 9pF Channel Capacitance during
Disconnect

• 100µA Supply Current in
Disconnect Mode

• Meets SCSI Hot Plugging Capability

•−300mA Sourcing Current for

Termination

• +40mA Sinking Current for Active
Negation

• Logic Command Disconnects all
Termination Lines

• Trimmed Termination Current to 7%

• Trimmed Impedance to 7%

• Current Limit and Thermal

Shutdown Protection

The UC5604 provides 9 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 UC5604 provides a disconnect feature which, when opened or driven
high, will disconnect all terminating resistors and disable the regulator,
greatly redu cing stan dby power. The output c hannels remain high imped­ance even without Termpwr applied.

The UC5604 is pin-for-pin compatibl e with its predeces sor, the UC5603 - 9
line Active Terminator. The only functiona l di fference be tw een the UC5604
and UC5603 is the absence of the negative clamps. Parametrically, the
UC5604 has a 7 % tol er ance o n im peda nce and current compared to a 3%
tolerance on the UC5603 and the sink current is reduced from 300mA to
40mA. Custom power packages are utilized to allow normal operation at
full power conditions (1.2 watts).

Internal circuit trimming is utilized, first to trim the impedance to a 7% toler­ance, and the n most importantly, to trim the output current to a 7% toler­ance, as close to the max SCSI spec as possible, which maximiz es noise
margin in fast SCSI operation.

Other features include thermal shutdown and current limit.
This device is offered in low thermal resistance versions of the industry

standard 16 pin narrow body SO IC, 16 pin ZIP (zig-zag in line package)
and 24 pin TSSOP.

UC5604

BLOCK DIAGRAM

3/97

UDG-94064

Circuit Design Patented

ABSOLUTE MAXIMUM RATINGS

Termpwr V o ltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V

Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V

Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5A

Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to +150°C

Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −55°C to +150°C

Lead Temperature (Soldering, 10 Sec.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C

Unless otherwise specified all voltages are with respe ct to G r ou nd . C urre nt s are pos i­tive into, negative out of the specified terminal.
Consult Packaging Section of Unitrode Integrated Circuits databook for thermal limita­tions and consid era ti ons of packages.

RECOMMENDED OPERATING CONDITIONS

Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8V to 5.25V

Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V

Disconnect Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to Termpwr

CONNECTION DIAGRAMS

DIL-16 (Top View)
N or J Package

TSSOP-24 (Top View)
PWP Package

UC5604

SOIC-16 (Top View)
DP Package

* DP packag e pi n 5 serves as signal groun d; pin s 4, 12, 13
serve as heatsink/ground.

* PWP pack ag e pi n 5 se rve s as sig na l gro un d; pins 6, 7, 8, 9,
17, 18, 19, and 20 serve as heatsink/ground.

ZIP-16 (Top View)
Z Package

Note: Drawings are not to scale.

2