UC5609

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 of UC5609 remain high impedance even without Termpwr applied.

Internal circuit trimming of UC5609 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.

Other features of UC5609  include 4.0 to 5.25V Termpwr, thermal shutdown and current limit.

This UC5609 is offered in low thermal resistance versions of the industry standard 28 pin wide body SOIC, 28 pin wide body TSSOP, and 28 pin PLCC, as well as 24 pin DIP.