General Description
The DS2127 Ultra3 LVD/SE SCSI terminator provides
low-voltage differential (LVD)/single-ended (SE) terminations for 14 SCSI lines. Through the voltage on the
DIFF_CAP pin, the device detects the types of drivers
on the bus. If the device is connected in an LVD-only
bus, the DS2127 provides LVD termination. If any single-ended devices are connected to the bus, the
DS2127 uses SE termination. If any high-voltage differential (HVD) devices are connected to the bus, the
DS2127 isolates itself from the SCSI bus. The mode
change has a built-in delay that is determined by an
integrated SPI-3 mode change filter/delay. The terminating resistors can also be disconnected from the bus
by asserting the ISO pin.
For the LVD termination, the DS2127 provides 14 precisely trimmed resistors. Each resistor is biased with
two current sources to a fail-safe state. For SE termination, the DS2127 provides 14 precision 110Ω resistors
and one regulator for active-negation bias.
Applications
SCSI Array Backplane
SCSI Cables
Features
♦ Fully Compliant with Ultra2, Ultra3, Ultra160, and
Ultra320 SCSI Standards
♦ Provides LVD/SE Termination for 14 Signal Pairs
♦ Auto-Selection of LVD or SE Termination
♦ 5% Tolerance on SE and LVD Termination
Resistance
♦ Low 3pF Power-Down Capacitance
♦ Built-In Mode-Change Filter/Delay
♦ On-Board Thermal-Shutdown Circuitry
♦ SCSI Bus Hot-Plug Compatible
♦ Fully Supports Actively Negated SE SCSI Signals
DS2127
Ultra3 LVD/SE SCSI 14-Line Terminator
______________________________________________ Maxim Integrated Products 1
Pin Configuration
Ordering Information
Rev 1; 3/04
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
查询DS2127供应商
PART TEMP RANGE
PINPACKAGE
DS2127 0°C to +70°C 48 LQFP DS2127
TOP
MARK
TOP VIEW
REF
R1N
R1P
V
HS_GND
HS_GND
HS_GND
HS_GND
HS_GND
HS_GND
TPWR
R14N
R14P
12111098765432
13
R2P
14
R2N
15
R3P
16
R3N
17
R4P
18
R4N
19
R5P
R5N
R6P
R6N
R7P
R7N
20
21
22
23
24
2526272829303132333435
SE
GND
LVD
DS2127
HS_GND
HS_GND
HS_GND
LQFP
HS_GND
HS_GND
HS_GND
DIFFSENS
DIFF_CAP
1
36
ISO
48
R13N
47
R13P
46
R12N
45
R12P
44
R11N
43
R11P
42
R10N
41
R10P
40
R9N
39
R9P
38
R8N
37
R8P
DS2127
Ultra3 LVD/SE SCSI 14-Line Terminator
2 _____________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(TPWR = V
TPWR(MIN)
to V
TPWR(MAX)
, TA= 0°C to +70°C, unless otherwise noted.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Voltage Range on All Pins Relative to Ground ......-0.3V to +6.0V
V
REF
Continuous Output Current....................................±200mA
Operating Temperature Range...............................0°C to +70°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +160°C
Soldering Temperature .......................................See IPC/JEDEC
J-STD-020A Specification
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TPWR Operating Supply Range
(Note 1)
TPWR SUPPLY CURRENT
TPWR Supply Current (All Lines
Open)
LVD TERMINATION (Applies to each line pair, 1 to 14 in LVD mode)
Differential-Mode Termination
Resistance
Common-Mode Termination
Resistance
Differential-Mode Bias V
Common-Mode Bias V
SE TERMINATION (Applies to single-ended terminators, 1 to 14 in SE mode)
Single-Ended Mode Termination
Resistance
Termination Current I
SE Voltage Reference V
Pin Leakage With ISO high 400 nA
Single-Ended GND Resistance R
TERMINATOR PIN CAPACITANCE
Terminator Pin Capacitance C
V
REGULATOR
REF
1.25V Regulator Output Voltage V
1.25V Regulator Short-Circuit
Source Current
1.25V Regulator Short-Circuit
Sink Current
V
TPWR
I
TPWR_LVD
I
TPWR_SE
I
TPWR_ISO
R
DM
R
CM
DM
CM
R
SE
REF
GND
REF_LVD
I
SOURCE
I
SINK
LVD 2.7 3.3 5.5
SE 4 5.0 5.5
LVD SCSI mode 32
SE SCSI mode 10
ISO mode (terminators disabled) 750 µA
100 110 Ω
RP and RN shorted together
(V
CM(MAX)
All lines open 100 125 mV
RP and RN shorted together (Note 1) 1.15 1.25 1.35 V
RSE = (VLX - 0.2) / ILX, where VLX = voltage
at terminator pin with pin unloaded and
SE
I
LX
the pin forced to 0.2V
Signal level at 0.2V, all lines low -21 -24 -25.4
Signal level at 0.5V -18 -22.4
Measured at RP pins, I = 10mA 20 60 Ω
With ISO high (Note 2) 3 pF
IN
0.5V ≤ V
and RN lines simultaneously
V
REF
V
REF
= 2V, V
= current for each terminator pin with
≤ 2.0V, VCM applied to all R
CM
= 0V -375 -700 -1000 mA
= 3.3V 170 300 700 mA
CM(MIN)
= 0.5V)
P
110 165 Ω
104.5 110 115.5 Ω
2.7 2.85 3.0 V
1.15 1.25 1.35 V
mA
mA
V