TI UC5604DPTR

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 reducing standby power. The output channels remain high impedance even without Termpwr applied. The UC5604 is pin-for-pin compatible with its predecessor, the UC5603 - 9 line Active Terminator. The only functional difference between the UC5604 and UC5603 is the absence of the negative clamps. Parametrically, the UC5604 has a 7% tolerance on impedance and current compared to a 3% tolerance on the UC5603 and the sink current is reduced from 300 mA to 40 mA. 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 then most importantly, to trim the output current to a 7% tolerance, as close to the max SCSI 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) and 24 pin TSSOP. Circuit Design Patented

• 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