TL-SCSI285 [TI]
FIXED-VOLTAGE REGULATORS FOR SCSI ACTIVE TERMINATION; 固定电压稳压器的SCSI有源终端
| 型号： | TL-SCSI285 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | FIXED-VOLTAGE REGULATORS FOR SCSI ACTIVE TERMINATION |
| 文件： | 总6页 (文件大小：84K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
PW PACKAGE
(TOP VIEW)
Fully Matches Parameters for SCSI
Alternative 2 Active Termination
Fixed 2.85-V Output
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
±1% Maximum Output Tolerance at
HEAT
SINK
HEAT
SINK
T = 25°C
J
0.7-V Maximum Dropout Voltage
620-mA Output Current
GND
OUTPUT
GND
INPUT
±2% Absolute Output Variation
Internal Overcurrent-Limiting Circuitry
Internal Thermal-Overload Protection
Internal Overvoltage Protection
HEAT
SINK
HEAT
SINK
HEAT SINK – These terminals have
an internal resistive connection to
ground and should be grounded or
electrically isolated.
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.
KC PACKAGE
(TOP VIEW)
OUTPUT
GND
INPUT
The GND terminal is in electrical
contact with the mounting base.
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
the330-Ωresistorsrequiredforeachtransmissionlinewithapassiveterminationscheme, reducingsignificantly
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
CHIP
PLASTIC
POWER
(KC)
SURFACE
MOUNT
(PW)
FORM
(Y)
T
J
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.
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.
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.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
absolute maximum ratings over operating virtual junction temperature range (unless otherwise
†
noted)
Continuous input voltage, V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 V
I
Operating virtual junction temperature range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to 150°C
J
Package thermal impedance, θ (see Notes 1 and 2): KC package . . . . . . . . . . . . . . . . . . . . . . . . . . . 22°C/W
JA
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
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°C
stg
†
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 T (max), θ , and T . The maximum allowable power dissipation at any allowable
J
JA
A
ambient temperature is P = (T (max) – T )/θ . Operating at the absolute maximum T of 150°C can impact reliability. Due to
D
J
A
JA
J
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
UNIT
MIN
MAX
Input voltage, V
Input voltage, V
T = 25°C
V
V
I
J
T = 0°C to 125°C
J
3.55
5.5
620
500
125
I
KC package
PW package
0
0
0
Output current, I
mA
O
Operating virtual junction temperature range, T
°C
J
electrical characteristics, V = 4.5 V, I = 500 mA, T = 25°C (unless otherwise noted)
I
O
J
TL-SCSI285KC
‡
PARAMETER
UNIT
TEST CONDITIONS
V = 3.55 V to 5.5 V,
MIN
2.82
2.79
TYP
MAX
2.88
2.91
15
I
I
= 20 mA to 500 mA,
= 500 mA to 620 mA,
T = 25°C
2.85
O
I
J
Output voltage
V
V = 3.65 V to 5.5 V,
T = 0 to 125°C
J
O
I
Input regulation
Ripple rejection
V = 3.55 V to 5.5 V
I
5
–62
5
mV
dB
f = 120 Hz,
V
ripple
= 1 V
O(PP)
I
I
= 20 mA to 620 mA
= 20 mA to 500 mA
30
30
O
Output regulation
Output noise voltage
Dropout voltage
mV
µV
V
5
O
f = 10 Hz to 100 kHz
500
I
O
I
O
I
O
I
O
I
O
I
O
= 500 mA
= 620 mA
= 0
0.7
0.8
5
2
3
= 27 mA, equivalent 1 line asserted
6
Bias current
mA
= 500 mA, equivalent 18 lines asserted (8-bit)
= 620 mA
26
37
49
62
‡
Pulse-testing techniques are used to maintain the virtual junction temperature as close to the ambient temperature as possible. Thermal effects
mustbe taken into account separately. All characteristics are measured with a 0.1-µF capacitor across the input and a22.0-µFtantalumcapacitor
with equivalent series resistance of 1.5 Ω on the output.
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
electrical characteristics, V = 4.5 V, I = 500 mA, T = 25°C (unless otherwise noted)
I
O
J
TL-SCSI285PW
UNIT
†
PARAMETER
TEST CONDITIONS
MIN
2.82
2.79
TYP
MAX
2.88
2.91
15
T = 25°C
2.85
J
Output voltage
I
= 20 mA to 500 mA,
V = 3.55 V to 5.5 V
I
V
O
T = 0 to 125°C
J
Input regulation
Ripple rejection
Output regulation
Output noise voltage
Dropout voltage
V = 3.55 V to 5.5 V
I
5
–62
5
mV
dB
mV
µV
V
f = 120 Hz,
V
= 1 V
ripple O(PP)
I
O
= 20 mA to 500 mA
30
f = 10 Hz to 100 kHz
500
I
O
I
O
I
O
I
O
= 500 mA
= 0
0.7
5
2
3
Bias current
= 27 mA, equivalent 1 line asserted
= 500 mA, equivalent 18 lines asserted (8-bit)
6
mA
26
49
†
Pulse-testing techniques are used to maintain the virtual junction temperature as close to the ambient temperature as possible. Thermal effects
mustbe taken into account separately. All characteristics are measured with a 0.1-µF capacitor across the input and a22.0-µFtantalumcapacitor
with equivalent series resistance of 1.5 Ω on the output.
electrical characteristics, V = 4.5 V, I = 500 mA, T = 25°C
I
O
J
TL-SCSI285Y
†
PARAMETER
UNIT
TEST CONDITIONS
V = 3.55 V to 5.5 V
MIN
TYP
2.85
5
MAX
Output voltage
I
= 20 mA to 500 mA,
V
O
I
Input regulation
Ripple rejection
V = 3.55 V to 5.5 V
I
mV
dB
f = 120 Hz,
V
= 1 V
–62
5
ripple O(PP)
I
I
= 20 mA to 620 mA
= 20 mA to 500 mA
O
Output regulation
mV
5
O
Output noise voltage
f = 10 Hz to 100 kHz
500
2
µV
I
O
I
O
I
O
I
O
= 0
= 27 mA, equivalent 1 line asserted
3
Bias current
mA
= 500 mA, equivalent 18 lines asserted (8-bit)
= 620 mA
26
37
†
Pulse-testing techniques are used to maintain the virtual junction temperature as close to the ambient temperature as possible. Thermal effects
mustbe taken into account separately. All characteristics are measured with a 0.1-µF capacitor across the input and a22.0-µFtantalumcapacitor
with equivalent series resistance of 1.5 Ω on the output.
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
APPLICATION INFORMATION
TERMPWR
Connector
1N5817
110 Ω
1%
5-V
Logic
Supply
TL-SCSI285
OUTPUT
DB(0)
DB(1)
INPUT
GND
0.1 µF
ATN
BSY
ACK
RST
MSG
SEL
C/D
22 µF
Tantalum
+
0.1 µF
Ceramic
REQ
I/O
Figure 1. Typical Application Schematic
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL-SCSI285
FIXED-VOLTAGE REGULATORS
FOR SCSI ACTIVE TERMINATION
SLVS065F – NOVEMBER 1991 – REVISED JULY 1999
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.
ESR OF OUTPUT CAPACITOR
STABILITY
vs
vs
LOAD CURRENT
ESR
0.04
0.035
0.03
3
2.8
2.6
2.4
2.2
2
C
= 22.0 µF
Not Recommended
Potential Instability
Recommended Min ESR
Not Recommended
Potential Instability
L
I
C = 0.1 µF
T
J
= 25°C
1000 µF
Region of
Best Stability
0.025
0.02
Max ESR Boundary
1.8
1.6
1.4
1.2
1
400 µF
200 µF
0.015
0.01
Min ESR
Boundary
0.8
0.6
0.4
0.2
0
100 µF
22 µF
0.005
0
10 µF
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0
0.1
0.2
0.3
0.4
0.5
1/ESR
I
L
– Load Current – A
Figure 3
∆ I
L
Applied Load
Current
Load
Voltage
∆ V
L
Figure 2
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
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Copyright 1999, Texas Instruments Incorporated
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