DS2127 Datasheet, PDF (1/6 Pages) Maxim Integrated Products – Ultra3 LVD/SE SCSI 14-Line Terminator

Rev 1; 3/04
Ultra3 LVD/SE SCSI 14-Line Terminator
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 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
PART
DS2127
Ordering Information
TEMP RANGE
0°C to +70°C
PIN-
PACKAGE
48 LQFP
TOP
MARK
DS2127
Pin Configuration
TOP VIEW
R2P ¹³
R2N ¹⁴
R3P ¹⁵
R3N ¹⁶
R4P ¹⁷
R4N ¹⁸
R5P ¹⁹
R5N ²⁰
R6P 21
R6N 22
R7P 23
R7N 24
DS2127
48 _R13N
47 _R13P
46 _R12N
45 _R12P
44 _R11N
43 _R11P
42 _R10N
41 _R10P
40 R9N
39 R9P
38 R8N
37 R8P
LQFP
______________________________________________ Maxim Integrated Products 1
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