UCC5642 Datasheet, PDF (1/12 Pages) Texas Instruments – LVD-ONLY SCSI TERMINATOR WITH REGULATOR AND SPI-3 DELAY

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D LVD-Only Active Termination
D 2.7-V to 5.25-V Operation
D Differential Failsafe Bias
D Integrated SPI-3 Mode Change/Filter Delay
UCC5642
LVDĆONLY SCSI TERMINATOR
WITH REGULATOR AND SPIĆ3 DELAY
SLUS477 – FEBRUARY 2000 – REVISED DECEMBER 2000
D Thermal Packaging for Low Junction
Temperature and Better MTBF
D 2.85-V Regulator With Load Share
D Meets Ultra2 (SPI-2 LVD), Ultra3/Ultra160
(SPI-3) and Ultra320 (SPI-4) Standards
description
The UCC5642 is an LVD-only small computer system interface (SCSI) terminator that integrates the mode
change delay function required by the SPI-3 specification. The device senses what types of SCSI drivers are
present on the bus via the voltage on the DIFFSENS SCSI control line. Single-ended (SE) and high-voltage
differential (HVD) (EIA485) SCSI drivers are not supported. If the chip detects the presence of an SE or HVD
SCSI driver, it disconnects itself by switching all terminating resistors off the bus and enters a high-impedance
state. The terminator can also be commanded to disconnect the terminating resistors with the DISCNCT input.
Impedance is trimmed for accuracy and maximum effectiveness. Bus lines are biased to a failsafe state to
ensure signal integrity. A 2.85-V, 300-mA sourcing regulator on chip can share with two other UCC5642 devices
in a parallel configuration for a 900 mA total.
The UCC5642 is offered in a 36-pin QSOP (MWP) package for a temperature range of 0°C to 70°C.
block diagram
VCC 24
VOUTM 29
3.6 kΩ
4 kΩ
1.5 V
VCC TO 2.85 V REGULATOR
VOLTAGE
AMPLIFIER
CURRENT
AMPLIFIER
2.1 V
DIFFB ₅
0.6 V
TRMPWR 12
DIFFSENS
REF 1.3 V
DISCNCT 7
HS/GND 8
HS/GND 10
HS/GND 26
HS/GND 28
GND 32
10 µA
FILTER/
DELAY
HPD
LVD
SE
TTL DRIVERS
ENABLE
SOURCE/SINK
REGULATOR
LVD REF
1.25 V
SW1
ENABLE
124
56 mV
−₊
56 mV
+–
MODE
SW1
OTHER
SWITCHES
SE DOWN
LVD DOWN
HPD DOWN
DISCNCT OPEN
OPEN
DOWN
OPEN
OPEN
124
56 mV
–+
56 mV
+–
25 VREG
30 SHARE
31 LVD
6 DIFSENS
52
21 L1–
52
22 L1+
52
34 L9–
52
33 L9+
11
REG
UDG-00158
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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