LX5251CPW Datasheet LX5251CPW | P4-P6

Microsemi

Integrated Products Division

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

Page 4

Rev. 1.1, 2006-02-27

WWW.Microsemi .COM

LX5251

9-Line Multimode SCSI Terminator

P

R

ODUCTION

DATA SHEET

TM

®

ELECTRICAL CHARACTERISTICS (CONTINUED)

Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C≤ T

A

≤ 125°C, VTerm = 4.75V,

and DISCONNECT = L.

LX5251

Parameter Symbol Test Conditions

Min Typ Max

Units

`

DISCONNECT Section

Disconnect Thresholds V

TH

0.8 2.0 V

I

IL

DISC = 0V 100 nA

Input Current

I

IH

DISC = 2.4V 10 µA

`

MASTER/SLAVE Section

Master/Slave Thresholds V

TH(MS)

0.8 2.0 V

I

IL(MS)

Master/Slave = 0V 10 µA

Input Current

I

IH(MS)

Master/Slave = 2.4V 100 nA

Note 1: Guaranteed by design.

BLOCK DIAGRAM

DIFSENSE

M/S

DISC

DIFFB

Window

Comp.

LVD

SE

HVD

150

1.07 mA

52.5

VTERM

20

SE

HVD

LVD

HVD

SE

HVD

LVD

GND

LVD(-)

/SE

LVD(+)

/SE (Pseudo-GND)

1 of 9

Terminator

Pairs

POWER

ON

&

MODE

DELAY

LATCH

DISC

1.25V

10mA

I-Limited

1.3V

Source

DISC

22.4mA

I-Limited

2.7V

Source

20K

24

11

13

14

12

1

2

Figure 1 – LX5251 Block Diagram

E

L

E

C

T

R

I

C

A

L

S

Microsemi

Integrated Products Division

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

Page 5

Rev. 1.1, 2006-02-27

WWW.Microsemi .COM

LX5251

9-Line Multimode SCSI Terminator

P

R

ODUCTION

DATA SHEET

TM

®

FUNCTIONAL PIN DESCRIPTION

PIN NAME DESCRIPTION

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

Negative signal termination lines for LVD mode. Signal termination lines for SE mode.

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

Positive signal termination lines for LVD mode. Psuedo-ground lines for SE mode.

V

TERM

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

decoupled by one 4.7

µF low-ESR capacitor for every three terminator devices. It is

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

frequency decoupling with 0.1

µF capacitors at V

TERM

pin.

DISCONNECT

Enables/Disables terminator. See Power Down Function Table for logic levels.

GND

Terminator ground pin. Connect to ground.

MASTER/SLAVE

Sometimes referred to as M/S pin in this datasheet. Used to select which terminator is the

controlling device. M/S 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 M/S pin. Please see DIFFSENSE and MASTER/SLAVE

Function Tables. Note: Must connect Diffsense signal to Diffsense pin of LX5251.

P

A

C

K

A

G

E

D

A

T

A

Microsemi

Integrated Products Division

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

Page 6

Rev. 1.1, 2006-02-27

WWW.Microsemi .COM

LX5251

9-Line Multimode SCSI Terminator

P

R

ODUCTION

DATA SHEET

TM

®

APPLICATION SCHEMATIC

1-

1+

9-

9+

VTERM

DIFFSENS

DISC

GND

1-

1+

9-

9+

VTERM

DIFFSENS

DISC

GND

1-

1+

9-

9+

VTERM

DIFFSENS

DISC

GND

VTERM

DIFFSENS

DISC

GND

1-

1+

9-

9+

VTERM

DIFFSENS

DISC

GND

1-

1+

9-

9+

VTERM

DIFFSENS

DISC

GND

1-

1+

9-

9+

Data Lines (9)

Control Lines (9)

HOST

PERIPHERAL

DISCONNECTDISCONNECT

TERMPOWER

* DIFFB pin not present on the LX5251CPW. Must connect Diffsense signal to Diffsens pin of each terminator.

4.7uF 4.7uF

LX5251

Figure 2 – Microsemi Application Schematic

A

P

L

I

C

A

T

I

O

N

S

LX5251CPW

LX5251CPW

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