Rainbow Electronics DS2127 - Manual

General Description
The DS2127 Ultra3 LVD/SE SCSI terminator provides
low-voltage differential (LVD)/single-ended (SE) termi-
nations 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 sin-
gle-ended devices are connected to the bus, the
DS2127 uses SE termination. If any high-voltage differ-
ential (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 termi-
nating resistors can also be disconnected from the bus
by asserting the ISO pin.
For the LVD termination, the DS2127 provides 14 pre-
cisely trimmed resistors. Each resistor is biased with
two current sources to a fail-safe state. For SE termina-
tion, the DS2127 provides 14 precision 110
Ω 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
R13N
R13P
R12N
R12P
R11N
R11P
R10N
R10P
R9N
R9P
R8N
R8P
R2P
R2N
R3P
R3N
R4P
R4N
R5P
R5N
R6P
R6N
R7P
R7N
13
14
15
16
17
18
19
20
21
22
23
24
48
47
46
45
44
43
42
41
40
39
38
37
LQFP
GND
SE
LVD
HS_GND HS_GND HS_GND HS_GND HS_GND HS_GND
DIFF_CAP DIFFSENS
ISO
25 26 27 28 29 30 31 32 33 34 35 36
12 11 10 9 8 7 6 5 4 3 2 1
R1N R1P V
REF
HS_GND HS_GND HS_GND HS_GND HS_GND HS_GND TPWR R14N R14P
DS2127
TOP VIEW
Pin Configuration
Ordering Information
Rev 0; 7/03
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.
PART TEMP RANGE
PIN-
PACKAGE TOP
MARK
DS2127 0°C to +70 °C 48 LQFP DS2127