18-Bit Switchable Active SCSI-2 Bus Terminator
Description
MCCS142236
18-Bit Switchable Active SCSI-2 Bus Terminator (110Ω)
With Voltage Regulator
The MCCS142236 is a precision 18−bit switchable active SCSI−2 bus terminator with an on−board 2.
85V regulator.
When the Disconnect pin is LOW according to the truth table below, the MCCS142236 provides 110Ω ±5% precision resistor pull−ups to a 2.
85V reference for termination of 18−bits in a SCSI−2 standard bus system interface.
When the Disconnect pin is HIGH, the device outputs are in the high impedance state on all 18 bits.
The regulator is also turned off, greatly reducing standby power.
Even with no Termpwr applied, the outputs remain in the high impedance state.
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18−BIT SWITCHABLE ACTIVE SCSI−2
BUS TERMINATOR
• Complies With SCSI and SCSI−2 Standards • Pin Compatible With UC5601, UC5602 and UC5608 • For Opposite Disconnect Polarity See ON Semiconductor’s
MCCS142238
• 18 Switchable 110Ω Terminating Resistors • 4pF Channel Capacitance During Disconnect • Fully Supports Active Negation (Sinks Minimum of 220mA) • Built−In 2.
85V Regulator With Low Dropout Voltage • Very Low Supply Current When Resistors Are Disabled (30μA Max) • −650mA Source Current • Thermal Shutdown Protection • Thin Profile Surface Mount Package: 28−Lead SOIC
DW SUFFIX 28−LEAD SOIC WIDE
CASE 751F−05
The regulator has a guaranteed dropout voltage of less than 900mV, allowing regulation of supply voltages less than 4.
0V.
The MCCS142236 is protected by thermal shutdown.
Other features include low disconnect current (30μA), over 220mA of active negation current sink capability, and 4pF disconnect capacitance.
In 8−bit SCSI applications (“A” cable), only one MCCS142236 is needed at each end of the SCSI cable in order to terminate the 18 active signal lines.
In 16−bit WIDE SCSI applications (“P” cable), either two MCCS142236s, one each of the MCCS142236 and MCCS142237, or three MCCS142237s would be needed at each end of the SCSI cable in order to properly terminate the 27 active signal lines.
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