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LX5248

9 - LINE LVD SCSI TERMINATOR

Microsemi Corporation 

UltraMAX

PRODUCT DATABOOK 1996/1997

9-LINE LVD SCSI TERMINATOR

PRELIMINARY DATA SHEET

LX5248/LX5249

FUNCTIONAL PIN DESCRIPTION

Pin

Designator

1-, 2-, 3-, 4-, 5-, 6-, 8-, 8-, 9-/

Description

Negative signal termination lines.

1+, 2+, 3+, 4+, 5+, 6+, 7+, 8+, 9+/ Positive signal termination lines.

VTERM

DISCONNECT/

Power supply pin for terminator. Connect to SCSI bus TERMPWR. Must be decoupled by one 4.7µF

low-ESR capacitor for every three terminator devices. It is absolutely necessary to connect this pin to

the decoupling capacitor through a very low impedence (big traces on PCB). Keeping distances

very short from the decoupling capacitors to the VTERM pin is also critical. The value of the

decoupling capacitor is somewhat layout dependant and some applications may benefit from high-

frequency decoupling with 0.1µF capacitors right at VTERM pin.

Enables / disables terminator. See Power Down Function Table for logic level per device.

GND/

Terminator ground pin. Connect to ground.

MASTER / SLAVE/

Sometimes referred to as M/S pin in this data sheet. Used to select which terminator is the control-

ling device. MASTER/SLAVE pin High or Open enables the DIFFSENSE output drive. Please see

MASTER/SLAVE Function Table.

DIFFSENSE/

This is a dual function pin. It drives the SCSI bus DIFFSENS line. It is also the sense pin to detect the

SCSI bus mode (LVD, SE or HVD). DIFFSENSE output drive can be disabled with Low level on the

MASTER/SLAVE pin. Please see DIFFSENSE and MASTER/SLAVE Function Tables. Internally

connected to DIFFB pin through 20kOhm resistor.

DIFFB/

Internally connected to DIFFSENSE pin through 20kOhm resistor. It can be used as a mode sense

pin when the device is a non-controlling terminator (MASTER/SLAVE pin is Low). An RC filter

(20kOhm / 0.1µF) is not required on the LX5249, as it has an internal timer.

SE/

Single-ended output; when High, terminator is operating in SE mode.

LVD/

Low Voltage Differential output. When High, terminator is operating in LVD mode.

HVD/

High Voltage Differential output. When High, terminator is operating in HVD mode.

HEATSINK/

Attached to die mounting pad, but not bonded to GND pin. Pins should be considered a heat sink

only, and not a true groung connection. It is recommended that these pins be connected to ground,

but can be left floating.

Copyright © 2001

Rev. 0.6 1/01

5

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