UCC5619
DESCRIPTION
UCC5619 provides 27 lines of active termination for a SCSI (Small Com-
puter Systems Interface) parallel bus. The SCSI standard recommends ac-
tive termination at both ends of the cable.
The UCC5619 is ideal for high performance 5V SCSI systems. During dis-
connect the supply current is typically only 100
A, which makes the IC at-
tractive for lower powered systems.
The UCC5619 is designed with a low channel capacitance of 2.5pF, which
eliminates effects on signal integrity from disconnected terminators at in-
terim points on the bus.
The power amplifier output stage allows the UCC5619 to source full termi-
nation current and sink active negation current when all termination lines
are actively negated.
The UCC5619, as with all Unitrode terminators, is completely hot pluggable
and appears as high impedance at the teminating channels with V
TRMPWR
= 0V or open.
Internal circuit trimming is utilized, first to trim the 110
impedance, and
then most importantly, to trim the output current as close to the maximum
SCSI-3 specification as possible, which maximizes noise margin in fast
SCSI operation.
Other features include thermal shutdown and current limit. This device is
offered in low thermal resistance versions of the industry standard 36 pin
wide body QSSOP (MWP).
Consult SSOP-36 (MWP QSSOP-36) Packaging Diagram for exact dimen-
sions.
27-Line SCSI Terminator With Reverse Disconnect
BLOCK DIAGRAM
FEATURES
Complies with SCSI, SCSI-2, SCSI-3,
SPI and FAST-20 (Ultra) Standards
2.5pF Channel Capacitance during
Disconnect
100A Supply Current in Disconnect
Mode
4V To 7V Operation
110 Termination
Completely Meets SCSI Hot Plugging
900mA Sourcing Current for
Termination
+500mA Sinking Current for Active
Negation
Logic Command Disconnects all
Termination Lines
Trimmed Impedance to 5%
Current Limit and Thermal Shutdown
Protection
SLUS265A - OCTOBER 1998 - REVISED - APRIL 2002
UDG-96108
Circuit Design Patented
2
UCC5619
ABSOLUTE MAXIMUM RATINGS
TRMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V
Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V
Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5A
Storage Temperature . . . . . . . . . . . . . . . . . . .
-65 C to +150 C
Junction Temperature . . . . . . . . . . . . . . . . . . .
-55 C to +150 C
Lead Temperature (Soldering, 10 Sec.). . . . . . . . . . . . . +300 C
Currents are positive into, negative out of the specified terminal.
Consult Packaging Section of Databook for thermal limitations
and considerations of packages.
LINE5
LINE6
LINE7
LINE22
LINE21
LINE19
LINE20
REG
LINE9
LINE8
GND*
LINE26
LINE27
LINE23
LINE24
LINE25
GND*
GND*
GND*
36
35
34
33
32
31
30
29
28
27
1
2
3
4
5
6
7
8
9
10
GND*
11
12
13
14
15
26
25
24
23
22
16
17
18
21
20
19
LINE12
LINE11
LINE10
DISCNCT
LINE13
LINE14
LINE1
LINE2
LINE17
LINE18
TRMPWR
GND*
LINE16
LINE15
LINE4
LINE3
* MWP package pins 8 - 10 and 26 - 28 serve as heatsink/
ground.
CONNECTION DIAGRAM
QSSOP-36 (Top View)
MWP Package
ELECTRICAL CHARACTERISTICS
Unless otherwise stated, these specifications apply for T
A
= 0C to 70C,
TRMPWR = 4.75V, DISCNCT = 4.75V, T
A
= T
J
.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Supply Current Section
TRMPWR Supply Current
All Termination Lines = Open
1
2
mA
All Termination Lines = 0.2V
630
650
mA
Power Down Mode
DISCNCT = 0V
100
200
A
Output Section (Termination Lines)
Termination Impedance
(Note 3)
104.5
110
115.5
Output High Voltage
(Note 1)
2.6
2.8
3.0
V
Max Output Current
V
LINE
= 0.2V, T
J
= 25C
-22.1 -23.3
-24
mA
V
LINE
= 0.2V
-20.7 -23.3
-24
mA
V
LINE
= 0.2V, TRMPWR = 4V, T
J
= 25
C (Note 1)
-21
-23
-24
mA
V
LINE
= 0.2V, TRMPWR = 4V (Note 1)
-20
-23
-24
mA
V
LINE
= 0.5V
22.4
mA
Output Leakage
DISCNCT = 0V, TRMPWR = 0V to 5.25V
10
400
nA
Output Capacitance
DISCNCT = 0V (Note 2)
2.5
4
pF
3
UCC5619
PIN DESCRIPTIONS
DISCNCT: Taking this pin low causes all channels to
become high impedance, and the chip to go into
low-power mode; a high state or leaving it open allows
the channels to provide normal termination.
GND: Ground reference for the IC.
LINE1 - LINE27: 110
termination channels.
REG: Output of the internal 2.7V regulator; bypass with a
4.7 F capacitor to GND.
TRMPWR: Power for the IC; bypass with a 4.7 F
capacitor to GND.
ELECTRICAL CHARACTERISTICS
Unless otherwise stated, these specifications apply for T
A
= 0C to 70C,
TRMPWR = 4.75V, DISCNCT = 4.75V, T
A
= T
J
.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Regulator Section
Regulator Output Voltage
2.6
2.8
3.0
V
Drop Out Voltage
All Termination Lines = 0.2V
0.4
0.8
V
Short Circuit Current
V
REG
= 0V
-650
-900 1300
mA
Sinking Current Capability
V
REG
= 3.5V
300
500
900
mA
Thermal Shutdown
170
C
Thermal Shutdown Hysteresis
10
C
Disconnect Section
Disconnect Threshold
0.8
1.5
2.0
V
Input Current
DISCNCT = 0V
20
60
A
Note 1: Measuring each termination line while other 26 are low (0.2V).
Note 2: Ensured by design. Not 100% tested in production.
Note 3: Tested by measuring I
OUT
with V
OUT
= 0.2V and V
OUT
with no load, then calculate:
Z
V
N L
V
I
at
V
OUT
OUT
=
. . .
.
0 2
0 2
11
29
25
TERMPWR
DISCNCT
DATA BYTES
1 AND 2
+2 PARITY BITS
7
REG
4.7
F
4.7
F
TO SCSI BUS
TERMPWR
17
LINE1
LINE27
CONTROL
BYTES
TO DRIVERS
AND
RECEIVERS
UCC5619
Figure 1. Typical wide SCSI bus configuration using the UCC5619
UDG-98072
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