Datasheet UCC5639FQPTR, UCC5639FQP Datasheet (Texas Instruments)

UCC5639

Multimode SCSI 15 Line Terminator with Reverse Disconnect

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)
and Ultra3 Standards

• 2.7V to 5.25V Operation

• Differential Failsafe Bias

• Thermal packaging for low junction

temperature and better MTBF.

BLOCK DIAGRAM

2.05V

34DIFFB

0.6V

DESCRIPTION

The UCC5639 Multimode SCSI Terminator provides a smooth transition
into the next generation of the SCSI Parallel Interface (SPI-2). 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 UCC5639 can not be used
on a HVD, EIA485, differential SCSI bus. If the UCC5639 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 effec­tiveness. 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 perform­ance analog functions necessary to implement SPI-2 termination in a sin­gle monolithic device.

The UCC5639 is offered in a 48 pin LQFP package for a temperature range
of 0°C to 70°C.

HIGH PO WER
DIFFERENTIAL

LOW VOLT AGE
DIFFERENTIAL

SINGLE ENDED

(NOISE LOAD)

REF

1.3V

–15mA ≤ I
50µA ≤ I

SOURCE

SINK

≤ –5mA

≤ 200µA

1.3V
35 DIFFSENS

DISCNCT

03/99

REF

2.7V

REF

1.25V

36

3TRMPWR

HS/GND

27

GND

4-9

SOURCE/SINK REGULATOR

MODE

DISCNCT

SE

LVD

HS/GND

ALL SWITCHES

UP

DOWN

OPEN

28-33

REG

10

4.7µF .

110

124

110

124

56mV

–+

56mV

+–

SE GND SWITCH

56mV

–+

56mV

+–

SE GND SWITCH

52.5

52.5

52.5

52.5

12

11

2

1

L1–

L1+

L15–

L15+

UDG-98110

UCC5639

ABSOLUTE MAXIMUM RATINGS

TRMPWR Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6V

Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . 0V to TRMPWR

Package Dissipation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2W

Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C

Junction Temperature. . . . . . . . . . . . . . . . . . . –55°C to +150°C

Lead Temperature (Soldering, 10 sec.). . . . . . . . . . . . . +300°C

Recommended Operating Conditions . . . . . . . . . 2.7V to 5.25V

Currents are positive into negative out of the specified terminal.
Note: Consult Packaging Section of Databook for thermal limi­tations and considerations of package.

RECOMMENDED OPERATING CONDITIONS

TRMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.25V

Temperature Ranges . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C

CONNECTION DIAGRAMS

(TOP VIEW)
FQP Package

HS/GND
HS/GND
HS/GND

REG

L1+
L1–

12

10

L8+

GND
HS/GND
HS/GND
HS/GND

L8–

L2+
L2–
L3+
L3–
L4+
L4–
L5+
L5–
L6+
L6–
L7+
L7–

11

13
14
15
16

17
18
19
20

21
22
23
24

25

26

8

7

9

27

29

30

28

6

5

313233

HS/GND
HS/GND
HS/GND

TRMPWR
L15–
L15+

2

4

3

1

L14–

48
47

L14+
L13–

46

L13+

45

L12–

44

L12+

43

L11–

42

L11+

41

L10–

40

L10+

39
38

L9–

37

35

34

L9+

36

DISCNCT
DIFSENS
DIFFB
HS/GND
HS/GND
HS/GND

ELECTRICAL CHARACTERISTICS

Unless otherwise stated, these specifications apply for TA= TJ= 0°C to 70°C,

TRMPWR = 3.3V.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

TRMPWR Supply Current Section

TRMPWR Supply Current LVD Mode 20 25 mA

SE Mode 1.6 10 mA
Disabled Terminator 250 400

Regulator Section

1.25V Regulator LVD Mode 1.15 1.25 1.35 V

1.25V Regulator Source Current V

1.25V Regulator Sink Current V

= 0V –375 –700 –1000 mA

REG

= 3.3V 170 300 700 mA

REG

1.3V Regulator DIFSENS 1.2 1.3 1.4 V

1.3V Regulator Source Current V

1.3V Regulator Sink Current V

= 0V –15 –5 mA

REG

= 3.3V 50 200 µA

REG

2.7V Regulator SE Mode 2.5 2.7 3.0 V

2.7V Regulator Source Current V

2.7V Regulator Sink Curren V

= 0V –375 –700 –1000 mA

REG

= 3.3V 170 300 700 mA

REG

Differential Termination Section

Differential Impedance 100 105 110 Ω
Common Mode Impedence (Note 2) 110 150 165 Ω
Differential Bias Voltage 100 125 mV
Common Mode Bias 1.15 1.25 1.35 V
Output Capacitance Single Ended Measurement to Ground (Note 1) 3 pF

µA

2

UCC5639

ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for T

TRMPWR = 3.3V.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Single Ended Termination Section

Impedance

Termination Current Signal Level 0.2V, All Lines Low –21 –24 –25.4 mA

Output Leakage 400 nA
Output Capacitance Single Ended Measurement to Ground (Note 1) 3 pF
Single Ended GND SE Impedance I= 10mA 20 60

Disconnect and Diff Buffer Input Section

DISCNCT
DISCNCT
Diff Buffer Single Ended to LVD Threshold 0.5 0.7 V
Diff Buffer LVD to HPD Threshold 1.9 2.2 V
DIFFB Input Current –10 10

Note 1: Guaranteed by design. Not 100% tested in production.

Note 2:

Threshold 0.8 2.0 V
Input Current 10 30 µA

12

.

Z

=

CM

II

[]

VCM V VCM V

(.)(.)

V

–

+−

06 06

where VCM=voltage measured with L+ tied to L– and zero current applied

VL V

−(.)02

X

Z

=

Signal Level 0.5V –18 –22.4 mA

IL

X

, (Note 3)

= TJ= 0°C to 70°C,

A

102.3 110 117.7

Ω

Ω

µA

Note 3: VL

= Output voltage for each terminator minus output pin (L1– through L15–) with each pin unloaded.

X

= Output current for each terminator minus output pin (L1– through L15–) with the minus output pin forced to 0.2V.

IL

X

PIN DESCRIPTIONS

DIFFB: Diff sense filter pin should be connected at a

0.1µF capacitor.
DIFFSENS: The SCSI bus Diff Sense line to detect what

types of devices are connected to the SCSI bus.

DISCNCT

when it is not at the end of the bus. The disconnect pin
high enables the terminator.

: Disconnect pin shuts down the terminator

LINE

n

–: Signal line active line for single ended or nega-

tive line in differential applications for the SCSI bus.

LINE

n

+: Ground line for single ended or positive line for

differential applications for the SCSI bus.
REG: Regulator bypass pin, must be connected to a

4.7µF capacitor.
TRMPWR: V

2.7V to 5.25V supply.

IN

3

APPLICATION INFORMATION

The UCC5639 is a Multi-mode active terminator with se­lectable single ended (SE) and low voltage differential
(LVD) SCSI termination integrated into a monolithic com­ponent. Mode selection is accomplished with the “diff
sense" signal.

The diff sense signal is a three level signal, which is
driven at each end of the bus by one active terminator. A
LVD or multi-mode terminator drives the diff sense line to

1.3 V. If diff sense is at 1.3 V, then bus is in LVD mode. If
a single ended SCSI device is plugged into the bus, the
diff sense line is shorted to ground. With diff sense
shorted to ground, the terminator changes to single
ended mode to accommodate the SE device. If a HVD
device is plugged in to the bus, the diff sense line is
pulled high and the terminator shuts down.

The diff sense line is driven and monitored by the termi­nator through a 50Hz noise filter at the DIFFB input pin.
A set of comparators, that allow for ground shifts, deter­mine the bus status as follows. Any diff sense signal be­low 0.5V is single ended, between 0.7V and 1.9V is LVD
and above 2.2V is HVD.

In the single ended mode, a multi-mode terminator has a
110Ω terminating resistor connected to a 2.7V termina­tion voltage regulator. The 2.7V regulator is used on all
Unitrode terminators designed for 3.3V systems. This re­quires the terminator to operate in specification down to

2.7V TRMPWR voltage to allow for the 3.3V supply toler­ance, an unidirectional fusing device and cable drop. At
each L+ pin, a ground driver drives the pin to ground,
while in single ended mode. The ground driver is spe­cially designed so it will not effect the capacitive balance
of the bus when the device is in LVD or disconnect mode.
The device requirements call for 0.5pF balance on the
lines of a differential pair. The terminator capacitance has
to be a small part of the capacitance imbalance.

Layout is very critical for Ultra2 and Ultra3 systems.
Multi-layer boards need to adhere to the 120Ω imped­ance standard, including connector and feed-through.
This is normally done on the outer layers with 4 mil etch

UCC5639

and 4 mil spacing between the runs within a pair, and a
minimum of 8 mil spacing to the next pair. This spacing
between the pairs reduces potential crosstalk. Beware of
feed-throughs and each through hole connection adds a
lot of capacitance. Standard power and ground plane
spacing yields about 1pF to each plane. Each feed­through will add about 2.5pF to 3.5pF. Enlarging the
clearance holes on both power and ground planes can
reduce the capacitance and opening up the power and
ground planes under the connector can reduce the ca­pacitance for through hole connector applications. Mi­crostrip technology is normally too low of impedance and
should not be used. It is designed for 50Ω rather than
120Ω differential systems.

Capacitance balance is critical for Ultra2 and Ultra3. The
balance capacitance standard is 0.5pF per line with the
balance between pairs of 2pF. The components are de­signed with very tight balance, typically 0.1pF between
pins in a pair and 0.3pF between pairs. Layout balance is
critical, feed-throughs and etch length must be balanced,
preferably no feed-throughs would be used. Capacitance
for devices should be measured in the typical application,
material and components above and below the circuit
board effect the capacitance.

Multi-mode terminators need to consider power dissipa­tion; the UCC5639 is offered in a power package with
heat sink ground pins. These heat sink/ground pins are
directly connected to the die mount paddle under the die
and conduct heat from the die to reduce the junction
temperature. These pins need to be connected to etch
area or a feed-through per pin connecting to the ground
plane layer on a multi-layer board.

In 3.3V TRMPWR systems, the UCC3912 should be
used to replace the fuse and diode. This reduces the
voltage drop, allowing for cable drop to the far end termi­nator. 3.3V battery systems normally have a 10% toler­ance. The UCC3912 is 150mV drop under LVD loads,
allowing 150mV drop in the cable system. All Unitrode
LVD and multi-mode terminators are designed for 3.3V
systems, operating down to 2.7V.

4

TYPICAL APPLICATION

UCC5639

4.7µF

3

36

TRMPWR

DISCNCT

REG

DATALINES (15)

DIFFB REGDIFFB

10 34

4.7µF

.

L1+
L1–

L9+
L9–

L10+
L10–

L13+
L13–

L1+
L1–

L5+
L5–

35

0.1µF

.

CONTROL LINES (9)

4 BITS OF THE HIGH BYTE

DIFF SENSE

20k

220k

HIGH BYTE 4 BITS

PLUS P ARITY

20k

L1+
L1–

L9+
L9–

L10+
L10–

L13+
L13–

35

DIFSENSDIFSENS

34 10

L1+
L1–

DATALINES (15)

L5+
L5–

0.1µF

.

TRMPWR

DISCNCT

3

36

4.7µF

Termp owerTermp ower

4.7µF

.

TRMPWR

3

36

DISCNCT

REG

10 34

SCSI CONTROLLER

DIFFSENS

4.7µF

.

L14+
L14–

DIFFB

L6+
L6–

L6+
L6–

LOW BYTE 8+ PARITY

L14+
L14–

34 10

TRMPWR

DISCNCT

REGDIFFB

3

36

4.7µF

UDG-98111

Note: A 220k resistor is added to ground to insure the transceivers will come up in single-ended mode when no terminator is en­abled.The controller DIFFSENS ties to the DIFFB pin on the terminators, only one RC network should be on a device.

UNITRODE CORPORATION
7 CONTINENTAL BLVD.• MERRIMACK, NH 03054
TEL. [phone] • FAX [phone]

5

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