TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
D
Fully Matches Parameters for SCSI
Alternative 2 Active Termination
D
Fixed 2.85-V Output
D
±1% Maximum Output Tolerance at
TJ = 25°C
D
0.7-V Maximum Dropout Voltage
D
620-mA Output Current
D
±2% Absolute Output Variation
D
Internal Overcurrent-Limiting Circuitry
D
Internal Thermal-Overload Protection
D
Internal Overvoltage Protection
description
The TL-SCSI285 is a low-dropout (0.7-V)
fixed-voltage regulator specifically designed for
small computer systems interface (SCSI)
alternative 2 active signal termination. The
TL-SCSI285 0.7-V maximum dropout ensures
compatibility with existing SCSI systems, while
providing a wide TERMPWR voltage range. At the
same time, the ±1% initial tolerance on its 2.85-V
output voltage ensures a tighter line-driver current
tolerance, thereby increasing the system noise
margin.
The fixed 2.85-V output voltage of the TL-SCSI285 supports the SCSI alternative 2 termination standard, while
reducing system power consumption. The 0.7-V maximum dropout voltage brings increased TERMPWR
isolation, making the device ideal for battery-powered systems. The TL-SCSI285, with internal current limiting,
overvoltage protection, ESD protection, and thermal protection, offers designers enhanced system protection
and reliability .
When configured as a SCSI active terminator, the TL-SCSI285 low-dropout regulator eliminates the 220-Ω and
the 330-Ω resistors required for each transmission line with a passive termination scheme, reducing significantly
the continuous system power drain. When placed in series with 110-Ω resistors, the device matches the
impedance level of the transmission cable and eliminates reflections.
The TL-SCSI285 is characterized for operation over the virtual junction temperature range of 0°C to 125°C.
AVAILABLE OPTIONS
PACKAGED DEVICES
T
J
PLASTIC
POWER
(KC)
SURFACE
MOUNT
(PW)
CHIP
FORM
(Y)
0°C to 125°C TL-SCSI285KC TL-SCSI285PWR TL-SCSI285Y
The PW package is only available taped and reeled. Chip forms are tested
at 25°C.
Copyright 1999, Texas Instruments Incorporated
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.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
GND
INPUT
GND
OUTPUT
PW PACKAGE
(TOP VIEW)
HEAT
SINK
HEAT
SINK
HEAT
SINK
HEAT
SINK
KC PACKAGE
(TOP VIEW)
OUTPUT
GND
INPUT
HEAT SINK – These terminals have
an internal resistive connection to
ground and should be grounded or
electrically isolated.
The GND terminal is in electrical
contact with the mounting base.
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
absolute maximum ratings over operating virtual junction temperature range (unless otherwise
noted)
†
Continuous input voltage, VI 7.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating virtual junction temperature range, TJ –55°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Package thermal impedance, θJA (see Notes 1 and 2): KC package 22°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . .
PW package 83°C/W. . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead temperature 1,6 mm (1/16 inch) from case for 60 seconds: KC or PW package 260°C. . . . . . . . . . . . .
Storage temperature range, T
stg
–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
†
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 under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
NOTES: 1. Maximum power dissipation is a function of TJ(max),
θ
JA
, and TA. The maximum allowable power dissipation at any allowable
ambient temperature is PD = (TJ(max) – TA)/
θ
JA
. Operating at the absolute maximum TJ of 150°C can impact reliability. Due to
variations in individual device electrical characteristics and thermal resistance, the built-in thermal overload protection may be
activated at power levels slightly above or below the rated dissipation.
2. The package thermal impedance is calculated in accordance with JESD 51, except for through-hole packages, which use a trace
length of zero.
recommended operating conditions
TL-SCSI285
MIN MAX
UNIT
Input voltage, V
I
TJ = 25°C V
Input voltage, V
I
TJ = 0°C to 125°C 3.55 5.5 V
p
KC package 0 620
Output current, I
O
PW package 0 500
mA
Operating virtual junction temperature range, T
J
0 125 °C
electrical characteristics, VI = 4.5 V, IO = 500 mA, TJ = 25°C (unless otherwise noted)
TL-SCSI285KC
PARAMETER
TEST CONDITIONS
‡
MIN TYP MAX
UNIT
p
IO = 20 mA to 500 mA, VI = 3.55 V to 5.5 V, TJ = 25°C 2.82 2.85 2.88
Output voltage
IO = 500 mA to 620 mA, VI = 3.65 V to 5.5 V, TJ = 0 to 125°C 2.79 2.91
V
Input regulation VI = 3.55 V to 5.5 V 5 15 mV
Ripple rejection
f = 120 Hz,
V
ripple
= 1 V
O(PP)
–62 dB
p
IO = 20 mA to 620 mA 5 30
Output regulation
IO = 20 mA to 500 mA 5 30
mV
Output noise voltage f = 10 Hz to 100 kHz 500 µV
p
IO = 500 mA 0.7
Dropout voltage
IO = 620 mA 0.8
V
IO = 0 2 5
IO = 27 mA, equivalent 1 line asserted 3 6
Bias current
IO = 500 mA, equivalent 18 lines asserted (8-bit) 26 49
mA
IO = 620 mA 37 62
‡
Pulse-testing techniques are used to maintain the virtual junction temperature as close to the ambient temperature as possible. Thermal effects
must be taken into account separately. All characteristics are measured with a 0.1-µF capacitor across the input and a 22.0-µF tantalum capacitor
with equivalent series resistance of 1.5 Ω on the output.
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics, VI = 4.5 V, IO = 500 mA, TJ = 25°C (unless otherwise noted)
TL-SCSI285PW
PARAMETER
TEST CONDITIONS
†
MIN TYP MAX
UNIT
p
TJ = 25°C 2.82 2.85 2.88
Output voltage
I
O
= 20 mA to
500 mA
,
V
I
= 3.55 V to 5.5
V
TJ = 0 to 125°C 2.79 2.91
V
Input regulation VI = 3.55 V to 5.5 V 5 15 mV
Ripple rejection
f = 120 Hz, V
ripple
= 1 V
O(PP)
–62 dB
Output regulation IO = 20 mA to 500 mA 5 30 mV
Output noise voltage f = 10 Hz to 100 kHz 500 µV
Dropout voltage IO = 500 mA 0.7 V
IO = 0 2 5
Bias current
IO = 27 mA, equivalent 1 line asserted 3 6
mA
IO = 500 mA, equivalent 18 lines asserted (8-bit) 26 49
†
Pulse-testing techniques are used to maintain the virtual junction temperature as close to the ambient temperature as possible. Thermal effects
must be taken into account separately. All characteristics are measured with a 0.1-µF capacitor across the input and a 22.0-µF tantalum capacitor
with equivalent series resistance of 1.5 Ω on the output.
electrical characteristics, VI = 4.5 V, IO = 500 mA, TJ = 25°C
TL-SCSI285Y
PARAMETER
TEST CONDITIONS
†
MIN TYP MAX
UNIT
Output voltage IO = 20 mA to 500 mA, VI = 3.55 V to 5.5 V 2.85 V
Input regulation VI = 3.55 V to 5.5 V 5 mV
Ripple rejection
f = 120 Hz, V
ripple
= 1 V
O(PP)
–62 dB
p
IO = 20 mA to 620 mA 5
Output regulation
IO = 20 mA to 500 mA 5
mV
Output noise voltage f = 10 Hz to 100 kHz 500 µV
IO = 0 2
IO = 27 mA, equivalent 1 line asserted 3
Bias current
IO = 500 mA, equivalent 18 lines asserted (8-bit) 26
mA
IO = 620 mA 37
†
Pulse-testing techniques are used to maintain the virtual junction temperature as close to the ambient temperature as possible. Thermal effects
must be taken into account separately. All characteristics are measured with a 0.1-µF capacitor across the input and a 22.0-µF tantalum capacitor
with equivalent series resistance of 1.5 Ω on the output.
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
TERMPWR
Connector
1N5817
5-V
Logic
Supply
TL-SCSI285
OUTPUTINPUT
GND
110 Ω
1%
0.1 µF
+
22 µF
Tantalum
0.1 µF
Ceramic
DB(0)
DB(1)
ATN
BSY
RST
MSG
ACK
SEL
C/D
I/O
REQ
Figure 1. Typical Application Schematic
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
COMPENSATION CAPACITOR SELECTION INFORMATION
The TL-SCSI285 is a low-dropout regulator. This means that the capacitance loading is important to the
performance of the regulator because it is a vital part of the control loop. The capacitor value and the equivalent
series resistance (ESR) both affect the control loop and must be defined for the load range and the temperature
range. Figures 2 and 3 can be used to establish the capacitance value and ESR range for best regulator
performance.
0.02
0.015
0.005
0
0 0.5 1 1.5 2 2.5 3
0.025
0.035
1/ESR
3.5 4 4.5 5
0.01
0.03
2.4
2.2
2
1.8
0 0.1 0.2 0.3
ESR – Equivalent Series Resistance –
2.6
2.8
3
0.4 0.5
0.04
1.2
1
0.8
0.6
1.4
1.6
0.4
0.2
0
ESR OF OUTPUT CAPACITOR
vs
LOAD CURRENT
STABILITY
vs
ESR
Ω
IL – Load Current – A
L
C
Applied Load
Current
Load
Voltage
∆ I
L
∆ V
L
Min ESR
Boundary
CL = 22.0 µF
CI = 0.1 µF
TJ = 25°C
10 µF
100 µF
400 µF
1000 µF
Figure 3
Max ESR Boundary
Not Recommended
Potential Instability
200 µF
Region of
Best Stability
Not Recommended
Potential Instability
Recommended Min ESR
22 µF
Figure 2
IMPORTANT NOTICE
T exas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
CERT AIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF
DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL
APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR
WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER
CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICA TIONS IS UNDERSTOOD T O
BE FULLY AT THE CUSTOMER’S RISK.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright 1999, Texas Instruments Incorporated
Loading...