Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 4

Copyright

 2000

Rev. 1.0a, 2003-06-30

LX5255

9-Line LVD SCSI Terminator

I N T E GRA T ED

PR ODUC T S

FUNCTIONAL PIN DESCRIPTION

1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-

Negative signal termination lines for LVD mode.

1+, 2+, 3+, 4+, 5+, 6+, 7+, 8+, 9+

Positive signal termination lines for LVD mode.

Power supply pin for terminator. Connect to SCSI bus VTERM. Must be

absolutely necessary to connect this pin to the decoupling capacitor through a very low

impedance (big traces to PCB). Keeping distances very short from the decoupling

capacitors is somewhat layout dependent and some applications may benefit from high

DISC

GND

Terminator ground pin. Connect to ground.

DIFSENS

Differential sense pin connected to system DIFFSENS line. Drives the SCSI bus

DIFSENS line to 1.3V.

DIFFB

Used to detect the SCSI bus mode (SE, LVD or HVD). Should be connected to a 4.7uF

capacitor to GND, and a 50KΩ resistor to the DIFFSENS pin (see Figure 2 on page 5).

5

BLOCK DIAGRAM

DIFSENS

DISC

DIFFB

LATCH

Window

Comp.

+

-

POWER

ON

&

MODE

DELAY

LVD

SE

HVD

150

1.07 mA

1.07 mA

52.5

52.5

VTERM

LVD

GND

LVD(-)

LVD(+)

1 of 9

Lines

10mA

I-Limited

1.3V

Source

HVD

SE

LVD

HVD

SE

24

13

11

10

12

3

2

DISC

1.25V

DISC

Figure 1 – LX5255CPW Block Diagram