LX5251
I N T E G R A T E D
P R O D U C T S
9-Line Multimode SCSI Terminator
P
RODUCTION
DATA SHEET
DESCRIPTION
The LX5251 is a multimode SCSI
terminator that is compatible with the
SCSI SPI-2 (Ultra2), SCSI SPI-3 (Ultra3
or Ultra160), and SCSI SPI-4 (Ultra320)
specifications developed by the T10
standards committee for low voltage
differential (LVD) termination, while
providing backwards compatibility to the
SCSI, SCSI-2, and SPI single-ended
specifications. Multimode compatibility
permits the use of legacy devices on the
bus without hardware alterations.
Automatic mode selection is achieved
through voltage detection on the
Diffsense line.
The LX5251 utilizes an industry
standard
LVD
architecture.
The
individual high bandwidth drivers
maximize channel separation, reduce
channel-to-channel noise and cross talk
to insure Ultra320 performance.
When the LX5251 is enabled, the
differential sense (DIFFSENSE) pin
supplies a voltage between 1.2V and
1.4V. In
application, this pin is tied to the DIFFSENSE
input of the corresponding LVD transceivers.
This action enables the LVD transceiver
function. DIFFSENSE is capable of supplying
a maximum of 15mA.
Tying the DIFFSENSE pin high places the
LX5251 in a HI-Z state indicating the presence
of an HVD device. Tying the pin low places
the part in a single-ended mode while also
signaling the multimode transceiver to operate
in a single-ended mode.
Recognizing the needs of portable and
configurable peripherals, the LX5251 has a
TTL compatible sleep/disable mode. During
this sleep/disable mode, power dissipation is
reduced to a meager 15uA while also placing
all outputs in a HI-Z state. Also during
sleep/disable mode, the DIFFSENSE function
is disabled and is placed in a HI-Z state.
The LX5251 also provides a master / slave
function. Driving this pin high or floating the
pin enables the 1.3V DIFFSENSE reference.
Driving the pin low disables the on board
DIFFSENSE reference and enables use of an
external master reference device.
KEY FEATURES
WWW .
Microsemi
.C
OM
Compliant with SCSI SPI-2
(Ultra2), SPI-3 (Ultra160), and
SPI-4 (Ultra320)
Auto-Selectable LVD or Single-
Ended Termination
Fast Response, No Output
Capacitors Required
Compatible with Active Negation
Drivers
15µA Supply Current in
Disconnect Mode
Logic Command Disconnects All
Termination Lines
Diffsense Line Driver
Ground Driver Integrated for
Single-Ended Operation
Current Limit and Thermal
Protection
Hot-Swap Compatible (Single-
Ended)
Available in 24-pin TSSOP
package
IMPORTANT:
For the most current data, consult
MICROSEMI’s
website:
http://www.microsemi.com
PRODUCT HIGHLIGHT
-
-
+
L X 5251
+
L X 5251
LX5251
LX5251
PACKAGE ORDER INFO
TSSOP
T
A
(°C)
PW
24-Pin
0 to 70
LX5251CPW
Note: Available in Tape & Reel.
Append the letter “T” to the part number. (i.e. LX5251CPWT)
Copyright
2002
Rev. 1.0a, 2003-07-28
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
LX5251
I N T E G R A T E D
P R O D U C T S
9-Line Multimode SCSI Terminator
P
RODUCTION
DATA SHEET
ABSOLUTE MAXIMUM RATINGS
Term Power (V
TERM
) ................................................................................................-0.3V to 7V
Operating Junction Temperature .......................................................................................150°C
Storage Temperature Range ............................................................................... -65°C to 150°C
Lead Temperature (Soldering 10 seconds) ........................................................................300°C
Note:
Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
PACKAGE PIN OUT
WWW .
Microsemi
.C
OM
1+
1-
2+
2-
3+
3-
4+
4-
5+
5-
DISC
GND
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
VTERM
NC
9-
9+
8-
8+
7-
7+
6-
6+
DIFFSENSE
M/Sb
THERMAL DATA
PW P
ACKAGE
(Top View)
PW
24 Pin Plastic TSSOP
100°C/W
N/C = Not internally connected
T
HERMAL
R
ESISTANCE
-J
UNCTION TO
A
MBIENT
,
θ
JA
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
The
θ
JA
numbers are guidelines for the thermal performance of the device/pc-board system.
All of the above assume no ambient airflow.
θ
JA
can vary significantly depending on
mounting technique.
MASTER/SLAVE FUNCTION TABLE
Master/Slave
L*
H
Open (Pull-Up)
DIFFSENSE Status
HI Z
1.3V
1.3V
0mA
10mA Source
10mA Source
* When in Low state, terminator will sense state of DIFFSENS line.
DIFFSENSE/POWER UP/POWER DOWN FUNCTION TABLE
P
ACKAGE
D
ATA
P
ACKAGE
D
ATA
DISCONNECT DIFFSENSE
L
L
L
H or Open
< 0.5V
0.7V – 1.9V
> 2.4V
X
Outputs
Status
Enable
Enable
Disable
Disable
Type
SE
LVD
HI-Z
HI-Z
Quiescent
Current
55mA
35mA
8mA
10µA
Copyright
2002
Rev. 1.0a, 2003-07-28
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
LX5251
I N T E G R A T E D
P R O D U C T S
9-Line Multimode SCSI Terminator
P
RODUCTION
DATA SHEET
RECOMMENDED MAX OPERATING CONDITIONS
WWW .
Microsemi
.C
OM
Parameter
LVD
SE
Signal Line Voltage
VTerm
Disconnect Input Voltage
Operating Junction Temperature
Symbol
V
TERM
Min
2.9
3.5
0
0
0
LX5251
Typ
Max
5.25
5.25
5.0
V
TERM
125
Units
V
V
V
°C
T
J
Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C
≤
T
A
≤
70°C, VTerm = 4.75V,
and DISC = L.
LX5251
Parameter
Symbol
Test Conditions
Units
Min
Typ
Max
LVD Terminator Section
VTerm Supply Current
Common Mode Voltage
Offset Voltage
Differential Terminator Impedance
Common Mode Impedance
Output Capacitance (Note 1)
Mode Change Delay
Diffsense Section
Diffsense Output Voltage
Diffsense Output Source Current
Diffsense Sink Current
Single Ended Section
VTerm Supply Current
Termination Output High Voltage
Output Current
Sink Current
Output Capacitance (Note 1)
Output Leakage
Ground Driver Impedance
SE
ICC
V
O
I
O
I
SINK
C
O
I
DDQ
I
HP
Z
G
V
OUT
= 0.2V
V
OUT
= 4V, All lines
DISC > 2.0V
DISC > 2.0V ; V
LINE
= 0 to 4V, T
A
= 25°
DISC > 2.0V ;V
TERM
= Open, V
LINE
= 2.7V,
T
A
= 25°
I = 1mA
All tem lines = Open, Master/Slave = 0V
All tem lines = 0.2V, Master/Slave = 0V
DISC > 2.0V; T
A
= 25°
2.5
18.5
40
55
250
15
2.7
22.5
65
3
2
1
100
75
290
35
3.1
24
mA
mA
µA
V
mA
mA
pF
µA
µA
Ω
V
DIFF
I
DIFF
I
SINK(DIFF)
V
DIFF
= 0V
V
DIFF
= 2.75V
1.2
5
20
1.3
1.4
15
200
V
mA
µA
LVD
ICC
V
CM
V
OS
Z
O
Z
CM
C
O
t
DF
Open circuit between (-) and (+) terminals
V
OUT
Differential = -1V to +1V
0.5V to 2V
DISC > 2.0V
Diffsense = 1.4V to 0V
100
115
All term lines open
DISC > 2.0V
1.125
100
100
110
35
15
1.25
112
105
150
45
35
1.375
125
110
195
3
300
mA
µA
V
mV
Ω
Ω
pF
ms
ELECTRICAL CHARACTERISTICS
E
LECTRICALS
E
LECTRICALS
Copyright
2002
Rev. 1.0a, 2003-07-28
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 3
LX5251
I N T E G R A T E D
P R O D U C T S
9-Line Multimode SCSI Terminator
P
RODUCTION
DATA SHEET
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
Units
Min
Typ
Max
DISCONNECT Section
Disconnect Thresholds
Input Current
MASTER/SLAVE Section
Master/Slave Thresholds
Input Current
Note 1: Guaranteed by design.
V
TH(MS)
I
IL(MS)
I
IH(MS)
Master/Slave = 0V
Master/Slave = 2.4V
0.8
100
2.0
10
V
µA
nA
V
TH
I
IL
I
IH
DISC = 0V
DISC = 2.4V
0.8
100
10
2.0
V
nA
µA
ELECTRICAL CHARACTERISTICS (CONTINUED)
WWW .
Microsemi
.C
OM
BLOCK DIAGRAM
VTERM
24
1.07 mA
1 of 9
Terminator
Pairs
SE
LVD
HVD
52.5
SE
LVD
150
HVD
52.5
22.4mA
I-Limited
2.7V
Source
LVD(-)
/SE
2
DISC
11
DISC
1
LVD(+)
/SE (Pseudo-GND)
1.25V
10mA
I-Limited
1.3V
Source
20
M/S
13
1.07 mA
12
GND
SE
DIFSENSE
14
20K
DIFFB
Window
HVD
Comp.
LVD
POWER
ON
&
MODE
DELAY
E
LECTRICALS
E
LECTRICALS
DISC
SE
LATCH
HVD
LVD
Figure 1 –
LX5251 Block Diagram
Copyright
2002
Rev. 1.0a, 2003-07-28
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 4
LX5251
I N T E G R A T E D
P R O D U C T S
9-Line Multimode SCSI Terminator
P
RODUCTION
DATA SHEET
FUNCTIONAL PIN DESCRIPTION
WWW .
Microsemi
.C
OM
P
IN
N
AME
1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-
1+, 2+, 3+, 4+, 5+, 6+, 7+, 8+, 9+
D
ESCRIPTION
Negative signal termination lines for LVD mode. Signal termination lines for SE mode.
Positive signal termination lines for LVD mode. Psuedo-ground lines for SE mode.
Power supply pin for terminator. Connect to SCSI bus VTERM. Musts be
decoupled by one 4.7
µ
F low-ESR capacitor for every three terminator devices. It is
V
TERM
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
µ
F capacitors at V
TERM
pin.
DISCONNECT
GND
Enables/Disables terminator. See Power Down Function Table for logic levels
.
Terminator ground pin. Connect to ground.
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.
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.
MASTER/SLAVE
DIFFSENSE
P
ACKAGE
D
ATA
P
ACKAGE
D
ATA
Copyright
2002
Rev. 1.0a, 2003-07-28
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 5
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