UCC5638 Datasheet, PDF (1/5 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, SCSI-3, SPI,
Ultra (Fast-20), Ultra2 (SPI-2 LVD
SCSI) and Ultra3/Ultra160 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 next generation of the SCSI Parallel Interface (SPI-2). It automati-
cally senses the bus, via DIFFB, and switches the termination to either sin-
gle 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 bus architectures. Single Ended
and Differential impedances and currents are trimmed for maximum effec-
tiveness. Fail Safe biasing is provided to insure signal integrity. 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 provides all the perform-
ance analog functions necessary to implement SPI-2 termination in a sin-
gle 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 .
SLUS271A - FEBRUARY 2000
35 DIFFSEN
12 L1–
11 L1+
2 L15–
1 L15+
UDG-98063