Austin AS1185F/XT Low dropout regulator Datasheet

LOW DROPOUT
REGULA
TOR
REGULAT
Austin Semiconductor, Inc.
Low Dropout Regulator
AS1185
PIN ASSIGNMENT
(Top View)
AVAILABLE AS MILITARY
SPECIFICATIONS
• Military Equipment Screening - MIL-STD-883, 1.2.2
10 Lead Flat Pack (F)
FEATURES
• Low Resistance Pass Transistor: 0.25Ω
• Dropout Voltage: 0.75V at 2.7A
• ±1% Reference Voltage
• Accurate Programmable Current Limit
• Shutdown Capability
• Internal Reference Available
• Standard 10-Lead Packages
• Full Remote Sense
• Low Quiescent Current: ≈ 2.5mA
• Good High Frequency Ripple Rejection
OPTIONS
• Packages
10 Lead Ceramic Flatpack
MARKINGS
GND
1
10
GND
FB
2
9
VOUT
VIN
3
8
NC
VREF
4
7
VOUT
VIN
5
6
NC
5V, 2.7A Regulator with 2.7A current limit
F
GENERAL DESCRIPTION
The AS1185 is a 2.7A low dropout regulator with adjustable
current limit and remote sense capability. It can be used as a
positive output regulator with floating input or as a standard
negative regulator with grounded input. The output voltage
range is 2.5V to 25V, with ±1% accuracy on the internal
reference voltage.
The AS1185 uses a saturation-limited NPN transistor as the
pass element. This device gives the linear dropout
characteristics of a FET pass element with significantly less die
area. High efficiency is maintained by using special
anti-saturation circuitry that adjusts base drive to track load
current. The “on resistance” is typically 0.25Ω.
Accurate current limit is programmed with a single 1/8W
external resistor, with a range of zero to three amperes. A
second, fixed internal limit circuit prevents destructive currents
if the programming current is accidentally overranged.
Assembly considerations for this package requires that
the fixed internal current limit circuit be bypassed at all times.
An external current limit resistor set to a maximum of 2.7A
must be used. Failure to do so on this package can result in
damage to the device.
Shutdown of the regulator output is guaranteed when the
program current is less than 1µA, allowing external logic
control of output voltage.
AS1185
Rev. 1.1 6/05
5.6K
AS1185
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please visit our web site at
www.austinsemiconductor.com
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
1
LOW DROPOUT
REGULA
TOR
REGULAT
Austin Semiconductor, Inc.
AS1185
ABSOLUTE MAXIMUM RATINGS1
Input Voltage ..................................................................................................................................................................................................... 35V
Input-Output Differential ................................................................................................................................................................................. 30V
FB Voltage .......................................................................................................................................................................................................... 7V
REF Voltage ........................................................................................................................................................................................................ 7V
Output Voltage .................................................................................................................................................................................................. 30V
Output Reverse Voltage .................................................................................................................................................................................. 2V
Operating Ambient Temperature Range
AS1185M ........................................................................................................................................................................... -55°C to 125°C
Operating Junction Temperature Range
Control Section
AS1185/IT ......................................................................................................................................................................... –40°C to 125°C
AS1185M/XT and /Mil .................................................................................................................................................. –55°C to 150°C
Power Transistor Section
AS1185/IT ........................................................................................................................................................................ –40°C to 150°C
AS1185M/XT and /MIL.................................................................................................................................................. –55°C to 175°C
Storage Temperature Range .......................................................................................................................................................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec)........................................................................................................................................................... 300°C
Theta J/C................................................................................................................................................................................................8.11°C/W
Max Power Dissipation (Tc = +125°C).......................................................................................................................................................3.0W
NOTES:
1. Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only
and functional operation of the device at these or any other conditions above those indicated in the operation section of this specification is not
implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
2. Reference voltage is quaranteed both at nominal conditions (no load, 25°C) and at worst-case conditions of load, line, power, and temperature.
An intermediate value can be calculated by adding the effects of these variables in the actual application.
3. Dropout voltage is tested by reducing input voltage until the output drops 1% below its nominal value. Tests are done at 0.5A and 2.7A. The
power transistor looks basically like a pure resistance in this range so that minimum differential at any intermediate current can be calculated by
interpolation; VDROPOUT = 0.25V + 0.25W • IOUT. For load current less than 0.5A, see graph.
4. “Minimum input voltage” is limited by base emitter voltage drive of the power transistor section, not saturation as measured in Note 3. For
output voltages below 4V, “minimum input voltage” specification may limit dropout voltage before transistor saturation limitation.
5. Supply current is measured on the ground pin, and does not include load current, RLIM, or output divider current.
6. The 25W power level is guaranteed for an input-output voltage of 8.3V to 17V. At lower voltages the 2.7A limit applies, and at higher voltages
the internal power limiting may restrict regulator power below 25W. See graphs.
7. Line and load regulation are measured on a pulse basis with a pulse width of »2ms, to minimize heating. DC regulation will be affected by thermal
regulation and temperature coefficient of the reference.
8. Guaranteed by design and correlation to other tests, but not tested.
9. TJMIN = – 40°C for AS1185I and –55°C for the AS1185M. Power transistor area and control circuit area have different maximum junction
temperatures. Control area limits are TJMAX = 125°C for the LT1185C and LT1185I and 150°C for the LT1185M. Power area limits are 150°C for
AS1185I and 175°C for AS1185M.
10. VSAT is the maximum specified dropout voltage; 0.25V + 0.25 • IOUT.
11. Current limit is programmed with a resistor from REF pin to GND pin. The value is 15k/ILIM.
12. For VIN – VOUT = 1.5V; VIN = 5V, VOUT = 3.5V. VOUT = 1V for all other current limit tests.
AS1185
Rev. 1.1 6/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
2
LOW DROPOUT
REGULA
TOR
REGULAT
Austin Semiconductor, Inc.
AS1185
ELECTRICAL CHARACTERISTICS: The • denotes specifications which apply over the
operating temperature range, otherwise specifications are at TA = 25°C. Adjustable version,
VIN = 7.4V, VOUT = 5V, IOUT = 1mA, RLIM = 5.6k, unless otherwise noted.
PARAMETER
Reference Voltage (@ FB Pin)
Rference Voltage Tolerance (@ FB Pin)2
MIN
TYP
2.37
0.3
MAX
±1
UNITS
V
%
•
1
±2.5
%
•
0.7
0.20
0.67
2.0
0.37
1.00
µA
V
V
0.05
0.3
%
0.002
4.0
4.3
3.6
0.01
%/V
V
V
A
A
A
A
A
CONDITION
VIN - VOUT = 5V, VOUT = VREF
1mA < IOUT < 2.7A
VIN - VOUT = 1.2V to VIN = 30V
P < 25W6, VOUT = 5V
TMAX9
Feedback Pin Bias Current
Dropout Voltage3
Load Regulation7
Line Regulation7
Minimum Input Voltage
Internal Current Limit
(See Graph for Guaranteed Curve)8, 12
External Current Limit Programming
Constant
External Current Limit Error
Quiescent Supply Current
Supply Current Change with Load
REF Pin Shutoff Current
Thermal Regulation
(See Applications Information)
Reference Voltage Temperature
Coefficient8
AS1185
Rev. 1.1 6/05
TMIN < TJ <
VOUT = VREF
IOUT = 0.5A, VOUT = 5V
IOUT = 2.7A, VOUT = 5V
IOUT = 5mA to 2.7A
VIN - VOUT = 1.5V to 10V, VOUT = 5V
VIN - VOUT = 1V to 20V, VOUT = 5V
IOUT = 1A4, VOUT = VREF
IOUT = 2.7A
1.5V < VIN - VOUT < 10V
3.3
3.1
2.0
1.0
0.2
4.2
4.4
4.2
2.6
1.0
VIN - VOUT = 15V
VIN - VOUT = 20V
VIN - VOUT = 30V
•
•
•
•
5k < RLIM < 15k, VOUT = 1V11
•
15k
•
0.02 ILIM
0.04 ILIM
0.06 ILIM + 0.03
0.09 ILIM + 0.05
A
A
4V < VIN < 25V5
•
2.5
3.5
mA
VIN - VOUT = VSAT10
VIN - VOUT > 2V
•
•
•
25
10
2
40
25
7
mA/A
mA/A
µA
0.005
0.014
%/W
0.003
0.01
%/°C
1A < ILIM < 2.7A
RLIM = 15k • A/ILIM
IOUT = 5mA, VOUT = VREF
VIN - VOUT = 10V, IOUT = 5mA to 2A
8
0.4
3
1.7
0.4
A•W
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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LOW DROPOUT
REGULA
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REGULAT
Austin Semiconductor, Inc.
SETTING OUTPUT VOLTAGE
External Current Limit
The AS1185 requires a resistor to set current limit. The value
of this resistor is 15k divided by the desired current limit (in
amps). The resistor for 2A current limit would be 15k/2A = 7.5k.
Tolerance over temperature is ±10%, so current limit is normally
set 15% above maximum load current. Foldback limiting can be
employed if short-circuit current must be lower than full load
current (see Typical Applications).
The AS1185 has internal current limiting which will override
The AS1185 output voltage is set by two external resistors
(see Figure 2). Internal reference voltage is trimmed to 2.37V so
that a standard 1% 2.37k resistor (R1) can be used to set divider
current at 1mA. R2 is then selected from:
R2 =
(VOUT - 2.37) R1
VREF
external current limit if power in the pass transistor is
excessive. The internal limit is ≈ 3.6A with a foldback
characteristic which is dependent on input-output voltage, not
output voltage per se (see Typical Performace Characteristics).
Assembly considerations for this package requires that
the fixed internal current limit circuit be bypassed at all times.
An external current limit resistor set to a maximum of 2.7A
must be used. Failure to do so on this package can result in
damage to the device.
for R1 = 2.37k and VREF = 2.37V, this reduces to:
R2 = VOUT - 2.37k
suggested values of 1% resistors are shown.
AS1185
Rev. 1.1 6/05
VOUT
R2 WHEN R1 = 2.37k
5V
5.2V
6V
12V
15V
2.67k
2.87k
3.65k
9.76k
12.7k
AS1185
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
4
LOW DROPOUT
REGULA
TOR
REGULAT
Austin Semiconductor, Inc.
AS1185
TYPICAL PERFORMANCE CHARACTERISTICS
AS1185
Rev. 1.1 6/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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LOW DROPOUT
REGULA
TOR
REGULAT
Austin Semiconductor, Inc.
AS1185
MECHANICAL DEFINITIONS*
Package Designator F
SYMBOL
A
B
C
D
E
F
G
H
I
ASI SPECIFICATIONS
MIN
MAX
0.250
0.260
0.250
0.260
0.900
--0.100
0.110
0.155
0.165
0.004
0.006
0.032
0.043
0.015
0.019
0.047
0.053
*All measurements are in inches.
AS1185
Rev. 1.1 6/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
6
LOW DROPOUT
REGULA
TOR
REGULAT
Austin Semiconductor, Inc.
AS1185
ORDERING INFORMATION
EXAMPLE:
AS1185F/MIL
Device Number Package Type Process
AS1185
F
/*
*AVAILABLE PROCESSES
IT = Industrial Temperature Range
XT = Extended Temperature Range
MIL = /883 equivalent processing
compliant to paragraph 1.2.2
SPACE = ASI’s DSCC approved
V-level/Class S (Space) Manufacturing Flow
AS1185
Rev. 1.1 6/05
-40oC to +85oC
-55oC to +125oC
-55oC to +125oC
-55oC to +125oC
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
7
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