ML6509_1245492

` Fully monolithic IC solution providing active termination for 9 lines of the SCSI bus
` Low dropout voltage (1V) linear regulator, trimmed for accurate termination current, with 300mA current source capability
` Output capacitance typically <5pF
` Disconnect mode - logic pin to disconnect terminator from the SCSI bus, <100µA
` Lowpower mode - for power conscious, portable system & peripheral applications, using less than 6" cables. (Equivalent to a 1mA current drive with a 2.5kW termination)
` Current sinking - can sink current >10mA per line to handle active negation driver overshoots above 2.85V
` Negative clamping on all lines to handle signal assertion transients
` Regulator can source 200mA and sink 50mA while
maintaining regulation
` Current limit & thermal shutdown protection
` Small and low profile package options; 16-pin SOIC
(300 mil), 20-pin TSSOP (1 mil height)

The ML6509_1245492 BiCMOS SCSI terminator provides active termination in a SCSI system with single ended drivers and receivers, in full compliance with the SCSI-1, SCSI-2 and SCSI-3 recommendations. It provides a 2.85V reference through an internal 1V dropout linear regulator. Active SCSI termination helps the system designer to effectively control analog transmission line effects like ringing, noise,crosstalk, ground bounce, etc. In addition it provides greater immunity to voltage drops on the TERMPWR line of the SCSI bus. The desired V-I characteristics for signal negation requires that the terminator source 024mA while maintaining 2.85V and for signal assertion preferably follow a linear slope of 110W. The ML6509_1245492 attempts to provide a V-I characteristic optimized to minimize the transmission line effects during both signal assertion and negation, using a MOSFET based architecture. The desired V-I characteristic of ML6509_1245492 is achieved by trimming one resistor in the control block. It provides negative clamping for signal assertion transients and current sink capability, to handle active negation driver overshoots above 2.85V, which is currently accomplished with external components in SCSI subsystems today. It provides a disconnect mode, where the terminator is completely disconnected from the SCSI bus and the output capacitance is < 5pF, typically.

One unique feature of the ML6509_1245492 is its support for a Low Power mode, for use in Notebook and portable computer applications, where it provides a 1mA (approximately  2.5KW termination) for less than 6" cable lengths. This minimizes the battery drain significantly in such systems. Current limiting and thermal shutdown protection are also provided. The nine line configuration of ML6509_1245492 is optimal for wide SCSI's 18, 27, or 45 line termination needs.