UCC5629

DESCRIPTION

The UCC5629 Multimode SCSI Terminator provides a smooth transition

into the next generation of the SCSI Parallel Interface (SPI-2). It automati-

cally senses the bus, via DIFFB, and switches the termination to either sin-

gle ended (SE) or low voltage differential (LVD) SCSI, dependent on which

type of devices are connected to the bus. The UCC5629 can not be used

on a HVD, EIA485, differential SCSI bus. If the UCC5629 detects a HVD

SCSI device, it switches to a high impedance state.

The Multimode terminator contains all functions required to terminate and

auto detect and switch modes for SPI-2 bus architectures. Single Ended

and Differential impedances and currents are trimmed for maximum effec-

tiveness. Fail Safe biasing is provided to insure signal integrity. Device/Bus

type detection circuitry is integrated into the terminator to provide automatic

switching of termination between single ended and LVD SCSI and a high

impedance for HVD SCSI. The multimode function provides all the perform-

ance analog functions necessary to implement SPI-2 termination in a sin-

gle monolithic device.

The UCC5629 is offered in a 48 pin LQFP package for a temperature range

of 0°C to 70°C.

Multimode SCSI 14 Line Terminator

FEATURES

• Auto Selection Single Ended (SE) or

Low Voltage Differential (LVD)

Termination

• Meets SCSI-1, SCSI-2, SCSI-3, SPI,

Ultra (Fast-20), Ultra2 (SPI-2 LVD)

and Ultra3 Standards

• 2.7V to 5.25V Operation

• Differential Failsafe Bias

• Thermal packaging for low junction

temperature and better MTBF.

• Reversed Polarity Disconnect

SLUS444 - NOVEMBER 1999

REF

1.25V

36

DISCNCT

REG

L1+

L14–

L14+

SOURCE/SINK REGULATOR

REF

1.3V

4.7

35

DIFFSEN

–15mA

≤ I

50

µA ≤ I

HPD

SE

34

DIFFB

0.6V

2.15V

52.5

2

52.5

1

110

10

REF

2.7V

SE GND SWITCH

3

TRMPWR

25

GND

4-9

HS/GND

28-33

HS/GND

L1–

124

52.5

12

52.5

11

110

124

10

µA

1.3V

(NOISE LOAD)

MODE

SE

LVD

DISCNCT

ALL SWITCHES

UP

DOWN

OPEN

SE GND SWITCH

56mV

–+

+–

–+

56mV

56mV

56mV

+–

27

26

LVD

BLOCK DIAGRAM

UDG-99156