Rev 1; 2/06
LVD SCSI 27-Line Regulator
General Description
The DS2129 is a triple-output voltage regulator for
27-line, low-voltage-differential (LVD) SCSI termination
for SPI-2 and SPI-3 applications using LVD termination
networks. The device provides reference voltages and
bias currents for LVD-termination resistor pi (π) net-
works. With a pi network (475Ω, 121Ω, 475Ω), the
DS2129 meets the common-mode bias, differential
bias, and termination-impedance requirements of SPI-2
(Ultra2) and SPI-3 (Ultra3). The device also provides a
1.3V output for DIFFSENSE signaling, and includes pro-
tection features such as thermal shutdown and active
current limiting.
♦
2.7V to 5.25V Operation
♦
Differential Fail-Safe Bias
Features
♦
Fully Compliant with SPI-2 and SPI-3
DS2129
Applications
SCSI Array Backplane
SCSI Cables
PART*
DS2129S
Ordering Information
VOLTAGE (V)
5
5
5
5
PIN-
PACKAGE
16 SO
16 SO
16 SO
16 SO
TOP
MARK**
DS2129
DS2129
DS2129
DS2129
Block Diagram
DS2129S+
DS2129S/T&R
DS2129S+T&R
TERMPWR
PTAT
BANDGAP
(1.25V)
REF125
THERMAL
SHUTDOWN
TS
+Denotes
lead-free package.
*All
devices rated for the commercial (0°C to +70°C) tempera-
ture range.
**A
“+” anywhere on the topmark denotes a lead-free package.
DS2129
REFERENCES
REF175
TS
1.75V
REG1
Pin Configuration
TOP VIEW
REF130
TS
N.C. 1
TERMPWR 2
0.75V
REG2
16 N.C.
15 N.C.
14 HS_GND
REG2 3
GND 4
DS2129
13 HS_GND
12 HS_GND
11 HS_GND
10 N.C.
9
N.C.
REF075
TS
1.3V
DIFFSENSE
HS_GND 5
REG1 6
DIFFSENSE 7
N.C. 8
GND
SO (150 mils)
______________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
LVD SCSI 27-Line Regulator
DS2129
ABSOLUTE MAXIMUM RATINGS
TERMPWR, DIFFSENSE, REG1, REG2 ....................-0.3V, +6.0V
REG1, REG2 Continuous Output Current.......................±200mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin SO (derate 13mW/°C above +70°C)........................1W
Operating Temperature Range...............................0°C to +70°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Soldering Temperature .......................................See IPC/JEDEC
J-STD-020A Specification
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(TERMPWR = 3.3V, T
A
= 0°C to +70°C, unless otherwise noted.) (Note 1)
PARAMETER
TERMPWR
TERMPWR Supply Current
TERMPWR Voltage
V
REF
REGULATOR
0.75V Regulator Output Voltage,
REG2
0.75V Regulator Source Current,
REG2
0.75V Regulator Sink Current,
REG2
0.75V Regulator Source Current
Limit
0.75V Regulator Sink Current
Limit
1.75V Regulator Output Voltage,
REG1
1.75V Regulator Source Current,
REG1
1.75V Regulator Sink Current,
REG1
1.75V Regulator Source Current
Limit
1.75V Regulator Sink Current
Limit
DIFFSENSE OUTPUT
DIFFSENSE Driver Output
Voltage
DIFFSENSE Driver Source
Current
DIFFSENSE Driver Sink Current
V
DSO
I
DSH
I
DSL
-5mA
≤
I
DIFFSENSE
≤
50µA
V
DIFFSENSE
= 0V
V
DIFFSENSE
= 2.4V
1.2
-5
100
1.3
1.4
-15
200
V
mA
µA
V
075
I
SRC_075
I
SINK_075
I
SRCL_075
I
SINKL_075
V
175
I
SRC_175
I
SINK_175
I
SRCL_175
I
SINKL_175
I
OUT
=
±125mA
V
OUT
= 0.25V
V
OUT
= 1.25V
V
OUT
= 0V
V
OUT
= 3.3V
I
OUT
=
±125mA
V
OUT
= 1.25V
V
OUT
= 2.25V
V
REF
= 0V
V
REF
= 3.3V
+200
-700
+700
1.7
1.75
+200
-700
+700
1.8
-200
0.7
0.75
0.8
-200
V
mA
mA
mA
mA
V
mA
mA
mA
mA
I
TERM
V
TERM
No load
2.7
40
5.25
mA
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_____________________________________________________________________
LVD SCSI 27-Line Regulator
ELECTRICAL CHARACTERISTICS
(continued)
(TERMPWR = 3.3V, T
A
= 0°C to +70°C, unless otherwise noted.) (Note 1)
PARAMETER
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
(Note 2)
Thermal-Shutdown Hysteresis
(Note 2)
For increasing temperature
+150
10
°C
°C
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DS2129
Note 1:
All voltages are referenced to ground.
Note 2:
Guaranteed by design and not production tested.
Typical Operating Circuit
TERMPWR
2.7V TO 5.25V
TERMPWR
4.7µF
DIFFSENSE
DIFFSENSE
DS2129
REG1
4.7µF
475Ω
1%
R1N
121Ω
1%
R1P
4.7µF
475Ω
1%
R2N
REG2
R26P
R27N
475Ω
1%
121Ω
1%
R27P
475Ω
1%
_____________________________________________________________________
3
LVD SCSI 27-Line Regulator
DS2129
Pin Description
PIN
1, 8, 9,
10, 15,
16
NAME
FUNCTION
Chip Information
TRANSISTOR COUNT: 3778 CMOS and 80 BIPOLAR
PROCESS: BiCMOS
SUBSTRATE CONNECTED TO GROUND
N.C.
No Connection. Do not connect pins.
Thermal Information
Thermal Resistance (junction-to-ambient):
θ
JA
= +77°C/W
Thermal Resistance (junction-to-case):
θ
JC
= +25°C/W
2
TERMPWR
Termination Power. Connect to SCSI
TERMPWR line and decouple with a
4.7µF ceramic capacitor.
Regulator 2, 0.75V Output. Decouple
with a 4.7µF ceramic capacitor.
Signal Ground
Heat-Sink Ground. Internally
connected to the mounting pad.
Should be connected to ground.
Regulator 1, 1.75V Output. Decouple
with a 4.7µF ceramic capacitor.
DIFFSENSE Output. Drives the SCSI
bus DIFFSENSE line.
3
4
5, 11–14
REG2
GND
HS_GND
6
7
REG1
DIFFSENSE
Detailed Description
The DS2129 provides three regulated outputs. The
REG1 provides a 1.75V output, and the REG2 provides
a 0.75V output. Both regulators can sink and source
200mA of current. These regulators are current-limited
to less than 700mA. The thermal-shutdown circuit dis-
ables the output buffers should the die temperature
exceed +150°C. With a pi network of resistors (475Ω,
121Ω, 475Ω) connected to these two outputs, the
DS2129 provides common-mode bias, differential bias,
and common impedance and differential impedance,
as required in a terminator specified in SPI-2 and SPI-3
standards for a SCSI system. The third regulator pro-
vides a 1.3V output for DIFFSENSE signaling.
4
_____________________________________________________________________
LVD SCSI 27-Line Regulator
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to
www.maxim-ic.com/packages).
SOICN .EPS
DS2129
INCHES
DIM
A
A1
B
C
e
E
H
L
MAX
MIN
0.069
0.053
0.010
0.004
0.014
0.019
0.007
0.010
0.050 BSC
0.150
0.157
0.228
0.244
0.016
0.050
MILLIMETERS
MAX
MIN
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
1.27 BSC
3.80
4.00
5.80
6.20
0.40
1.27
N
E
H
VARIATIONS:
1
INCHES
MILLIMETERS
MIN
4.80
8.55
9.80
MAX
5.00
8.75
10.00
N MS012
8
AA
14
AB
16
AC
TOP VIEW
DIM
D
D
D
MIN
0.189
0.337
0.386
MAX
0.197
0.344
0.394
D
A
e
B
A1
L
C
0∞-8∞
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL
DOCUMENT CONTROL NO.
REV.
21-0041
B
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________
5
© 2006 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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