Texas Instruments UCC5606PWPTR, UCC5606PWP, UCC5606N, UCC5606J, UCC5606DPTR Datasheet

UCC5606

9-Line 3-5 Volt SCSI Active Terminator, Reverse Disconnect

FEATURES

∙Complies with SCSI, SCSI-2 and SCSI-3 Standards

∙2.7V to 7V Operation

∙1.8pF Channel Capacitance during Disconnect

∙1μA Supply Current in Disconnect Mode

∙110 Ohm/2.5k Programmable Termination

∙Completely Meets SCSI Hot Plugging

∙-400mA Sourcing Current for Termination

∙+400mA Sinking Current for Active Negation Drivers

∙Trimmed Termination Current to 4%

∙Trimmed Impedance to 7%

∙Current Limit and Thermal Shutdown Protection

DESCRIPTION

The UCC5606 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 UCC5606 is ideal for high performance 3.3V SCSI systems. The key features contributing to such low operating voltage are the 0.1V drop out regulator and the 2.7V reference. The reduced reference voltage was necessary to accommodate the lower termination current dictated in the SCSI-3 specification. During disconnect the supply current is typically only 1μA, which makes the IC attractive for battery powered systems.

The UCC5606 is designed with an ultra low channel capacitance of 1.8pF, which eliminates effects on signal integrity from disconnected terminators at interim points on the bus.

The UCC5606 can be programmed for either a 110 ohm or 2.5k ohm termination. The 110 ohm termination is used for standard SCSI bus lengths and the 2.5k ohm termination is typically used in short bus applications. When driving the TTL compatible DISCNCT pin directly, the 110 ohm termination is connected when the DISCNCT pin is driven high, and disconnected when low. When the DISCNCT pin is driven through an impedance between 80k and 150k, the 2.5k ohm termination is connected when the DISCNCT pin is driven high, and disconnected when driven low. continued

BLOCK DIAGRAM

UDG-94067-1

Circuit Design Patented

5/95

Description Continued

The power amplifier output stage allows the UCC5606 to source full termination current and sink active negation current when all termination lines are actively negated.

The UCC5606 is pin for pin compatible with Unitrode’s other 9 line SCSI terminators, except that DISCNCT is now active low, allowing lower capacitance and lower voltage upgrades to existing systems. The UCC5606, as with all Unitrode terminators, is completely hot pluggable and appears as high impedance at the terminating channels with VTRMPWR = 0V or open.

ABSOLUTE MAXIMUM RATINGS

Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6A 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 respect to Ground. Currents are positive into, negative out of the specified terminal.

Consult Packaging Section of Unitrode Integrated Circuits databook for thermal limitations and considerations of packages.

RECOMMENDED OPERATING CONDITIONS

Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.25V Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V Disconnect Input Voltage . . . . . . . . . . . . . . . . . . 0V to Termpwr

SOIC-16 (Top View)

DP Package

* DP package pin 5 serves as signal ground; pins 4, 12, 13 serve as heatsink/ground.

Note: Drawings are not to scale.

UCC5606

Internal circuit trimming is utilized, first to trim the 110 ohm termination impedance to a 7% tolerance, and then most importantly, to trim the output current to a 4% tolerance, as close to the max SCSI-3 spec as possible, which maximizes 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 SOIC, 16 pin ZIP (Zig-Zag In Line package), 24 pin TSSOP and 28 pin PLCC.

CONNECTION DIAGRAMS

ZIP-16 (Top View)

Z Package

TSSOP-24 (Top View)

PWP Package

* PWP package pin 5 serves as signal ground; pins 6, 7, 8, 9, 17, 18, 19, and 20 serve as heatsink/ground.

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