Volta
ge R
e gula
tor
oltag
Re
gulator
AS29372
Austin Semiconductor, Inc.
LOW-DROPOUT VOLTAGE
REGULATOR
PIN ASSIGNMENT
(Top View)
AVAILABLE AS MILITARY
SPECIFICATIONS
!
7 Lead Flatpack (F)
MIL-STD-883, Class B
GND
1
FEATURES
High output voltage accuracy
Guaranteed 750mA output
! Low quiescent current
! Low dropout voltage
! Extremely tight load and line regulation
! Very low temperature coefficient
! Current and thermal limiting
! Input can withstand -20V reverse battery and +60V
positive transients
! Logic-controlled electronic shutdown
! Output programmable from 1.24V to 26V
! Available in a 7-lead flatpack package
!
!
SHDN 2
ADJ 3
VIN 4
VIN 5
6
OUT
GENERAL DESCRIPTION
APPLICATIONS
!
!
!
!
!
!
!
!
!
The AS29372 is an efficient voltage regulator with very low
dropout voltage and very low quiescent current. Key features
include protection against reversed battery, fold-back current
limiting, and automotive “load dump” protection. A logic
compatible input is provided, which allows the device to be
switched on and off.
Battery powered equipment
Cellular telephones
Laptop, notebook, and palmtop computers
PCMCIA VCC and VPP Regulation/Switching
Bar code scanners
Automotive electronics
SMPS post-regulator/DC to DC modules
High efficiency linear power supplies
OPTIONS
Package
7-Lead Flatpack
AS29372
Rev. 2.0 3/03
7 OUT
MARKING
For more products and information
please visit our web site at
www.austinsemiconductor.com
F
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
1
Volta
ge R
e gula
tor
oltag
Re
gulator
AS29372
Austin Semiconductor, Inc.
ABSOLUTE MAXIMUM RATINGS1
Power Dissipation............................................Internally Limited
Lead Temperature (Soldering, 5 seconds)..........................260°C
Storage Temperature Range..............................-65°C to +150°C
Operating Junction Temperature Range...........-40°C to +125°C
θJC = 14°C/W
Input Supply Voltage................................................-20V to +60V
Operating Input Supply Voltage*...................................2V to 26V
Adjust Input Voltage9,10...........................................-1.5V to +26V
Shutdown Input Voltage...........................................-0.3V to +30V
Error Comparator Output Voltage.........................-0.3V to +30V
*Across the full operating temperature, the minimum input
voltage range for full output current is 4.3V to 26V. Output
will remain in-regulation at lower output voltages and low
current loads down to an input of 2V at 25°C.
ELECTRICAL CHARACTERISTICS
Limits in standard typeface are for TJ = 25°C and limits in boldface apply over the full operating temperature range,
-40°C to +125°C. Unless otherwise specified, VIN = VOUT + 1V, IL = 5mA, CL = 10µF. The AS29372 are programmed for a
5V output voltage, and VSHUTDOWN < 0.6V.
SYMBOL
∆VO/∆T
PARAMETER
Output Voltage
(note 2)
Temperature Coef.
∆VO/∆VIN Line Regulation
∆VO/∆IL
VIN - VO
IGND
Load Regulation
Dropout Voltage
(note 5)
CONDITIONS
VIN = VOUT + 1V to 26V
IL = 2mA
IL = 5 to 700 mA
(note 3 & 4)
TYP
MAX
UNITS
20
100
ppm/°C
0.03
0.10
0.40
%
0.04
0.16
0.20
%
IL = 5mA
80
IL = 100mA
200
IL = 500mA
300
IL = 5mA, VO = 5 ± 0.1V
160
Ground Pin Current
IL = 100mA, VO = 5 ± 0.1V
(note 6)
1
IL = 500mA, VO = 5 ± 0.1V
8
∆VO/∆PD Thermal Regulation (note 9)
Reference Voltage (note 7)
Adjust Pin
Bias Current
AS29372
Rev. 2.0 3/03
MIN
0.05
1.204
20
150
180
250
320
450
600
250
300
2.5
3
13
16
0.2
1.26
40
60
mV
µA
mA
%/W
V
nA
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
2
Volta
ge R
e gula
tor
oltag
Re
gulator
AS29372
Austin Semiconductor, Inc.
ELECTRICAL CHARACTERISTICS (Cont.)
Shutdown Input
PARAMETER
Input Logic Voltage
Shutdown Pin
Input Current
MIN
CONDITIONS
Low (ON)
High (OFF)
TYP
MAX
0.7
2.0
VSHUTDOWN = 2.4V
30
VSHUTDOWN = 26V
450
Regulator Output
Current in
(note 8)
Shutdown
3
UNITS
V
50
100
600
750
µA
10
20
µA
NOTES:
1. Unless otherwise specified, VIN = VOUT = 1V, IL = 5mA, CL = 10µF, TJ = TA. Device shall be biased in accordance with
Figure 1 with VSHUTDOWN < 0.6V, VIN = 6V, RL = 300 kilohms ±1%.
2. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature
range.
3. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Changes in output voltage
due to heating effects are covered by the thermal regulation specification.
4. This parameter is tested up to 600mA; however, limits are guaranteed but not tested to 750mA.
5. Dropout voltage is defined as the input-to-output differential at which the output voltage drops 100mV below its
nominal value measured at 1V differential. At very low values of programmed output voltage, the minium input supply
voltage of 2V (2.3V over temperature) must be taken into account.
6. Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load
current plus the ground pin current.
7. VREF < VOUT < (VIN - 1V), 4.3V < VIN < 26V, 5mA < IL < 600mA, TJ < TJMAX.
8. See Figure 1 with RL > 150 kilohms, VSHUTDOWN > 2V, VIN < 26V, VOUT = 0.
9. Thermal regulation is defined as the change in output voltage at a time (t) after a change in power dissipation is applied,
excluding line and load regulation effects. Specification is for a 200mA load pulse at VIN = 20V (at 4W pulse) for
t = 10ms.
AS29372
Rev. 2.0 3/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
3
Volta
ge R
e gula
tor
oltag
Re
gulator
Austin Semiconductor, Inc.
AS29372
SCHEMATIC DIAGRAM
AS29372
Rev. 2.0 3/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
4
Volta
ge R
e gula
tor
oltag
Re
gulator
Austin Semiconductor, Inc.
AS29372
TYPICAL CHARACTERISTICS
AS29372
Rev. 2.0 3/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
5
Volta
ge R
e gula
tor
oltag
Re
gulator
Austin Semiconductor, Inc.
AS29372
TYPICAL CHARACTERISTICS (Cont.)
AS29372
Rev. 2.0 3/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
6
Volta
ge R
e gula
tor
oltag
Re
gulator
AS29372
Austin Semiconductor, Inc.
APPLICATIONS INFORMATION
External Capacitors
Reducing Output Noise
A 10µF (or greater) capacitor is required between the output
and ground to prevent oscillations due to instability. Most
types of tantalum or aluminum electrolytics will be adequate;
film types will work, but are costly and therefore not
recommended. Many aluminum electrolytics have
electrolytes that freeze at about -30°C, so solid tantalums are
recommended for operation below -25°C. The important
parameters of the capacitor are an effective series resistance
of about 5Ω or less and a resonant frequency above 500kHz.
The value of this capacitor may be increased without limit.
In reference applications it may be advantageous to reduce
the AC noise present at the output. One method is to reduce
the regulator bandwidth by increasing the size of the output
capacitor. This is relatively inefficient, as increasing the
capacitor from 1µF to 220µF only decreases the noise from
430µV to 160µVRMS for a 100kHz bandwidth at 5V output.
Noise can be reduced by a factor of four with the adjustable
regulators with a bypass capacitor across R1, since it reduces
the high frequency gain from 4 to unity. Pick
CBYPASS z
At lower values of output current, less output capacitance is
required for output stability. The capacitor can be reduced to
0.5µF for current below 10mA or 0.15µF for currents below
1mA. Adjusting the AS29372 to voltages below 5V runs the
error amplifier at lower gains so that more output capacitance
is needed. For the worst-case situation of 750mA load at
1.23V output (Output shorted to Adjust) a 22µF (or greater)
capacitor should be used.
1
2πR1 H 200 Hz
or about 0.01µF. When doing this, the output capacitor must
be increased to 10µF to maintain stability. These changes
reduce the output noise from 430µV to 100µVRMS for a
100kHz bandwidth at 5V output. With the bypass capacitor
added, noise no longer scales with output voltage so that
improvements are more dramatic at higher output voltages.
Programming the Output Voltage
The AS29372 may be programmed for any output voltage
between its 1.235V reference and its 26V maximum rating.
An external pair of resistors is required, as show in Figure 1.
The complete equation for the output voltage is
VOUT = VREF x {1 + R1/R2} - |IFB|R1
where VREF Is the nominal 1.235 reference voltage and IFB is
the Adjust pin bias current, nominally 20nA. The minimum
recommended load current of 1µA forces an upper limit of 1.2MΩ
on the value R2, if the regulator must work with no load (a
condition often found in CMOS in standby), IFB will produce a
-2% typical error in VOUT which may be eliminated at room
temperature by trimming R1. For better accuracy, choosing
R2 = 100k reduces this error to 0.17% while increasing the
resistor program current to 12µA. Since the AS29372 typically
draws 100µA at no load with SHUTDOWN open-circuited, this
is a negligible addition.
AS29372
Rev. 2.0 3/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
7
Volta
ge R
e gula
tor
oltag
Re
gulator
Austin Semiconductor, Inc.
AS29372
TYPICAL APPLICATIONS
*Minimum INPUT-OUTPUT voltage ranges from 40mV to 400mV, depending
on load current.
Figure 2. AS29372 Wide Input Voltage
Range Current Limiter
Figure 1. AS29372 Adjustable Regulator
*SHUTDOWN PIN LOW = ENABLE OUTPUT. Q1 ON = 3.3V, Q1 OFF = 5.0V.
Figure 3. AS29372 5.0V or 3.3V Selectable
Regulator with Shutdown
AS29372
Rev. 2.0 3/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
8
Volta
ge R
e gula
tor
oltag
Re
gulator
Austin Semiconductor, Inc.
AS29372
MECHANICAL DEFINITIONS*
Package Designator F
*All measurements are in inches. Drawing is not to scale.
AS29372
Rev. 2.0 3/03
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
9
Volta
ge R
e gula
tor
oltag
Re
gulator
AS29372
Austin Semiconductor, Inc.
ORDERING INFORMATION
EXAMPLE:
AS29372F/883
Device Number Package Type Process
AS29372
F
/*
*AVAILABLE PROCESSES
*AVAILABLE PROCESSES
IT = Industrial Temperature Range
XT = Extended Temperature Range
883C = MIL/883 equivalent processing
compliant to paragraph 1.2.2
AS29372
Rev. 2.0 3/03
-40oC to +85oC
-55oC to +125oC
-55oC to +125oC
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
10