UCC5630A
Multimode SCSI 9 Line Terminator
FEATURES
DESCRIPTION
• Auto Selection Single Ended (SE) or
Low Voltage Differential (LVD)
Termination
The UCC5630A 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 UCC5630A can not be used
on a HVD, EIA485, differential SCSI bus. If the UCC5630A detects a HVD
SCSI device, it switches to a high impedance state.
• Meets SCSI-1, SCSI-2, Ultra2 (SPI-2
LVD), Ultra3, Ultra160 (SPI-3) and
Ultra320 (SPI-4) Standards
• 2.7V to 5.25V Operation
• Differential Failsafe Bias
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.
• Thermal packaging for low junction
temperature and better MTBF
• Master/Slave Input
• Supports Active Negation
• 3pF Channel Capacitance
The UCC5630A is offered in a 36 pin SSOP package, as well as a 48 pin
LQFP package for a temperature range of 0°C to 70°C.
BLOCK DIAGRAM
HIPD LVD
35 34
SE
33
(NOISE LOAD)
REF 1.3V
HIPD
2.15V
1.3V
20 DIFSENS
DIFFB 21
LVD
SE
–15mA ≤ I
≤ –5mA
SOURCE
0.6V
50µA ≤ I
≤ 200µA
SINK
19
MSTR/SLV
110
124
SOURCE/SINK REGULATOR
SE REF 2.7V
56mV
52.5
52.5
–
+
5
4
L1–
L1+
LVD REF 1.25V
56mV
+
–
ALL
SWITCHES
MODE
SE GND SWITCH
56mV
SE
LVD
UP
110
124
10µA
DOWN
OPEN
OPEN
HIPD
52.5
52.5
ENABLE
SWITCHES
–
+
DISCNCT
17
DISCNCT
32 L9–
31 L9+
56mV
+
–
TRMPWR 36
SE GND SWITCH
18
8
9
10
26
27
28
1
PATENTED CIRCUIT DESIGN
GND
REG
HS/GND
UDG-98192
Note: Indicated pinout is for 36 pin SSOP package.
SLUS322C - SEPTEMBER 1999 - REVISED MARCH 2002