UCC5638_06 Datasheet, PDF (1/8 Pages) Texas Instruments – Multimode SCSI 15 Line Terminator

UCC5638
Multimode SCSI 15 Line Terminator
FEATURES
• Auto Selection Single Ended (SE) or
Low Voltage Differential (LVD)
Termination
• Meets SCSI-1, SCSI-2, Ultra2 (SPI-2
LVD SCSI), Ultra3, Ultra160 (SPI-3)
and Ultra320 (SPI-4) Standards
• 2.7V to 5.25V Operation
• Differential Failsafe Bias
• Thermal packaging for low junction
temperature and better MTBF.
BLOCK DIAGRAM
DESCRIPTION
The UCC5638 Multimode SCSI Terminator provides a smooth transition
into the LVD SCSI Parallel Interface (SPI-2, SPI-3, SPI-4). It automatically
senses the bus, via DIFFB, and switches the termination to either single
ended (SE) or low voltage differential (LVD) SCSI, dependent on which
type of devices are connected to the bus. The UCC5638 can not be used
on a HVD, EIA485, differential SCSI bus. If the UCC5638 detects a HVD
SCSI device, it switches to a high impedance state.
The Multimode terminator contains all functions required to terminate and
auto detect and switch modes for SPI-2, SPI-3 and SPI-4 bus architectures.
Single Ended and Differential impedances and currents are trimmed for
maximum effectiveness. Fail Safe biasing is provided to insure signal integ-
rity. Device/Bus type detection circuitry is integrated into the terminator to
provide automatic switching of termination between single ended and LVD
SCSI and a high impedance for HVD SCSI. The multimode function pro-
vides all the performance analog functions necessary to implement SPI-2
termination in a single monolithic device.
The UCC5638 is offered in a 48 pin LQFP package for a temperature range
of 0°C to 70°C.
2.15V
DIFFB 34
0.6V
REF
2.7V
REF
1.25V
10µA
HIGH POWER
DIFFERENTIAL
LOW VOLTAGE
DIFFERENTIAL
SINGLE ENDED
(NOISE LOAD)
REF
1.3V
1.3V
–15mA ≤ I_SOURCE ≤ –5mA
50µA ≤ I_SINK ≤ 200µA
SOURCE/SINK REGULATOR
MODE
SE
LVD
DISCNCT
ALL SWITCHES
UP
DOWN
OPEN
110
124
56mV
–+
56mV
+–
52.5
52.5
SE GND SWITCH
110
DISCNCT 36
TRMPWR 3
27
GND
HS/GND
4-9
HS/GND
28-33
124
56mV
–+
56mV
+–
52.5
52.5
SE GND SWITCH
10
REG
4.7µF .
SLUS271B - FEBRUARY 2000 - REVISED APRIL 2001
35 DIFFSEN
12 L1–
11 L1+
2 L15–
1 L15+
UDG-98063