MCCS142238 Datasheet, PDF (1/5 Pages) ON Semiconductor – 18-Bit Switchable Active SCSI-2 Bus Terminator

MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
18ĆBit Switchable Active
SCSIĆ2 Bus Terminator (110Ω)
With Voltage Regulator and
Inverted Disconnect
MCCS142238
The MCCS142238™ is a precision 18-bit switchable active SCSI-2 bus
terminator with an on-board 2.85V regulator. When the Disconnect pin is
HIGH according to the truth table below, the MCCS142238 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 LOW, 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.
18-BIT SWITCHABLE
ACTIVE SCSI-2
BUS TERMINATOR
• Complies With SCSI and SCSI-2 Standards
• Pin Compatible With UC5609
• For Opposite Disconnect Polarity See Motorola’s MCCS142236
• 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 (150µA Max)
• –650mA Source Current
• Thermal Shutdown Protection
• Thin Profile Surface Mount Package: 28-Lead SOIC
DW SUFFIX
28–LEAD WIDE SOIC PACKAGE
CASE 751F-04
The regulator has a guaranteed dropout voltage of less than 900mV, allowing regulation of supply voltages less than 4.0V. The
MCCS142238 is protected by thermal shutdown. Other features include low disconnect current (150µA), over 220mA of active
negation current sink capability, and 4pF disconnect capacitance.
In 8-bit SCSI applications (“A” cable), only one MCCS142238 is needed at each end of the SCSI cable in order to terminate the
18 active signal lines.
For information on “Power Dissipation for Active SCSI Terminators,” refer to Motorola Application Note AN1408/D, available
through the Motorola Design–NET Fax System as “HOT–DOC” Number 1083, or through the Motorola Literature Distribution
Center.
TRUTH TABLE
Disconnect
0
1
Output
Z
Terminated
MCCS and Mfax are trademarks of Motorola, Inc.
1/97
© Motorola, Inc. 1997
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