UC5609DWPTR

Lower Capacitance 18-Line 5V SE Terminator for SCSI and Fast SCSI with Reverse Disconnect 28-SOIC 0 to 70

DESCRIPON

The UC5609 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 bus cable.

The UC5609 is pin-for-pin compatible with its predecessors, the UC5601, UC5602 and UC5608 - 18 Line Active Terminators, except for the reverse disconnect sense. Parametrically the UC5609 has a 5% tolerance on impedance and current compared to a 3% tolerance on the UC5601 and the sink current is increased from 20 to 200mA. The low side clamps have been removed. Custom power packages are utilized to allow normal operation at full power conditions 2 Watts.

When in disconnect mode the terminator will disconnect all terminating resistors and disable the regulator, greatly reducing standby power. The output channels remain high impedance even without Termpwr applied.

Internal circuit trimming is utilized to trim the impedance to a 5% tolerance and, most importantly, to trim the output current to a 5% tolerance, as close to the max SCSI spec as possible, which maximizes noise margin in fast SCSI operation.

FEATURES

• Reverse Disconnect

• Complies with SCSI, SCSI-2 and SPI-2 Standards

• 6pF Channel Capacitance during Disconnect

• 100µA Supply Current in Disconnect Mode

• Meets SCSI Hot Plugging Capability

• −650mA Sourcing Current for Termination

• +200mA Sinking Current for Active Negation

• Provides Active Termination for 18 Lines

• Logic Command Disconnects all Termination Lines

• Trimmed Termination Current to 5%

• Trimmed Impedance to 5%

• Current Limit and Thermal Shutdown Protection