MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

1

REV 2

1/97

18Bit Switchable Active

SCSI2 Bus Terminator (110Ω)

With Voltage Regulator and

Inverted Disconnect

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

110

Ω ±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.

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 (150

µA), 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

Output

0

Z

1

Terminated

MCCS and Mfax are trademarks of Motorola, Inc.

MCCS142238

18-BIT SWITCHABLE

ACTIVE SCSI-2

BUS TERMINATOR

DW SUFFIX

28–LEAD WIDE SOIC PACKAGE

CASE 751F-04