MCCS142237DTR2 ON Semiconductor, MCCS142237DTR2 Datasheet

MCCS142237DTR2

Manufacturer Part Number

MCCS142237DTR2

Description

Manufacturer

ON Semiconductor

Type

SCSI Terminationr

Datasheet

1.MCCS142237DTR2.pdf (7 pages)

Specifications of MCCS142237DTR2

Termination Resistance (rt Or Rterm) (typ)

110Ohm

Number Of Bits

Operating Supply Voltage (typ)

Operating Supply Voltage (max)

5.25V

Package Type

TSSOP

Mounting

Surface Mount

Operating Temperature Classification

Commercial

Lead Free Status / RoHS Status

Not Compliant

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MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

9-Bit Switchable Active

SCSI-2 Bus Terminator (110 )

With Voltage Regulator

terminator with an on–board 2.85V regulator. The SCSI–2 standard

recommends the use of active terminations at both ends of every cable

segment in a SCSI system with single–ended drivers and receivers. The

MCCS142237 enables the designer to gain the benefits of active

termination: greater immunity to voltage drops on the TERMPWR

(TERMination PoWeR) line, enhanced high–level immunity, intrinsic

TERMPWR decoupling, and very low quiescent current consumption.

When the device is enabled (PD = HIGH), the MCCS142237 provides

110

9–bits in a SCSI–2 standard bus system interface. When PD is LOW, the

device is in the High Impedance State on all 9 bits.

regulation of input voltages less than 4.0V. Internal protective features

include thermal shutdown.

into each of the termination resistors when the signal line is low

(asserted). When the driver for a given signal line turns off, the terminator

will pull the signal line to 2.85V (quiescent state). To handle actively

negated SCSI signals, the regulator can sink over 220mA. When the

Power–Down pin (PD) is LOW, the power–down circuitry will turn off the transistors on each signal line. This isolates the

MCCS142237 from the signal lines and effectively removes it from the bus. The PD pin has an internal pull–up resistor. To place

the terminator into the active state, the PD pin should either be left open circuited or tied HIGH.

and both the VREF1 and VREF2 pins must be tied together externally. Each MCCS142237 requires a minimum 2.2 F capacitor

connected between the VREF pins and ground.

18 active signal lines. In 16–bit WIDE SCSI applications (“P” cable), three MCCS142237s would be needed at each end of the

SCSI cable in order to terminate the 27 active signal lines.

through the Motorola Design–NET Fax System, or through the Motorola Literature Distribution Center.

MCCS and Mfax are trademarks of Motorola, Inc.

1/97

Motorola, Inc. 1997

The regulator produces a 2.85V level and is capable of sourcing 24mA

Complies With SCSI and SCSI–2 Standards

Pin Compatible With DS2107, DS2107A and DS21S07A

9 Switchable 110 Terminating Resistors

Power–Down Mode Disengages Terminating Resistors

Built–In 2.85V Regulator

Guaranteed Maximum 1.0V Dropout Voltage

3pF Channel Capacitance During “Power–Down”

Thermal Shutdown Circuitry

Fully Supports Active Negation SCSI Signals

Regulator Short Circuit Protection

Thin Profile 20–Pin TSSOP and 16–Pin SOIC Packages

The MCCS142237 is a precision 9–bit switchable active SCSI–2 bus

The regulator has a dropout voltage of less than 1.0V, allowing

To ensure proper operation, both the TERMPWR1 and TERMPWR2 pins must be connected to the SCSI bus TERMPWR line

In 8–bit SCSI applications (“A” cable), two MCCS142237s are needed at each end of the SCSI cable in order to terminate the

For information on “Power Dissipation for Active SCSI Terminators,” refer to Motorola Application Note AN1408/D, available

precision resistor pull–ups to a 2.85V reference for termination of

TRUTH TABLE

REV 5

20–LEAD PLASTIC TSSOP PACKAGE

MCCS142237

16–LEAD WIDE SOIC PACKAGE

9–BIT SWITCHABLE

BUS TERMINATOR

ACTIVE SCSI–2

CASE 751G–02

CASE 948D–03

DW SUFFIX

DT SUFFIX

Terminated

Output

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MCCS142237DTR2 Summary of contents

Page 1

MOTOROLA SEMICONDUCTOR TECHNICAL DATA 9-Bit Switchable Active SCSI-2 Bus Terminator (110 ) With Voltage Regulator The MCCS142237 is a precision 9–bit switchable active SCSI–2 bus terminator with an on–board 2.85V regulator. The SCSI–2 standard recommends the use of active terminations ...

Page 2

MCCS142237 TERMPWR1 1 20 HS–GND HS–GND 8 13 VREF1 9 12 GND 10 11 Figure 1. 20–Lead Pinout (Top View) PIN DESCRIPTIONS 20–Lead ...

Page 3

MAXIMUM RATINGS* Symbol TERMPWR DC Supply Voltage V Line Voltage on Any Pin Relative to Ground I Reg Regulator Output Current t stg Storage Temperature Range V REF Reference Voltage * Maximum Ratings are those values beyond which damage to ...

Page 4

MCCS142237 TERMPWR 50k Thermal Shutdown Enable Logic PD TERMINATION POWER LINE TERMPWR1 2.2 F TERMPWR2 VREF1 VREF2 MCCS142237 2.2 F GND RECEIVERS BUS DRIVER TO RECEIVERS BUS DRIVER Figure 4. Typical SCSI Bus Configuration Using the MCCS142237 ...

Page 5

VREF AC CHARACTERISTICS (V REF = 2.85 50pF 6ns) Symbol Parameters t (connect) Max Enable Time, High Impedance to Termination Outputs t (disconnect) Max Disable Time, Termination to High ...

Page 6

MCCS142237 –A – – – 0.25 (0.010 –T – SEATING K PLANE 0.25 (0.010 PIN 1 IDENTIFICATION ...

Page 7

Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of ...

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