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oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc. LOW-DROPOUT VOLTAGE REGULATOR
AVAILABLE AS MILITARY SPECIFICATIONS
MIL-STD-883, Class B para 1.2.2 compliant
AS29372
PIN ASSIGNMENT
(Top View) 7 Lead Flatpack (F) 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
7 OUT
6 OUT
APPLICATIONS
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
GENERAL DESCRIPTION
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.
OPTIONS
Package 7-Lead Flatpack
MARKING
F
For more products and information please visit our web site at www.austinsemiconductor.com
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc.
ABSOLUTE MAXIMUM RATINGS1
Power Dissipation............................................Internally Limited Lead Temperature (Soldering, 5 seconds)..........................260C Storage Temperature Range..............................-65C to +150C Operating Junction Temperature Range...........-40C to +125C JC = 14C/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 25C.
AS29372
ELECTRICAL CHARACTERISTICS
Limits in standard typeface are for TJ = 25C and limits in boldface apply over the full operating temperature range, -40C to +125C. Unless otherwise specified, VIN = VOUT + 1V, IL = 5mA, CL = 10F. The AS29372 are programmed for a 5V output voltage, and VSHUTDOWN < 0.6V.
SYMBOL VO/T
PARAMETER Output Voltage (note 2) Temperature Coef. IL = 2mA
CONDITIONS
MIN
TYP 20 0.03
MAX 100 0.10 0.40 0.16 0.20 150 180 250 320 450 600 250 300 2.5 3 13 16 0.2 1.26 40 60
UNITS ppm/C %
VO/VIN Line Regulation VO/IL Load Regulation
VIN = VOUT + 1V to 26V
IL = 5 to 700 mA (note 3 & 4) IL = 5mA
0.04 80 200 300 160 1 8 0.05 1.204 20
%
VIN - VO
Dropout Voltage (note 5)
IL = 100mA IL = 500mA IL = 5mA, VO = 5 0.1V
mV
A
IGND
Ground Pin Current IL = 100mA, VO = 5 0.1V (note 6) IL = 500mA, VO = 5 0.1V
mA %/W V nA
VO/PD Thermal Regulation (note 9) Reference Voltage (note 7) Adjust Pin Bias Current
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc.
ELECTRICAL CHARACTERISTICS (Cont.) Shutdown Input
PARAMETER Input Logic Voltage Shutdown Pin Input Current Low (ON) High (OFF) VSHUTDOWN = 2.4V VSHUTDOWN = 26V CONDITIONS MIN 2.0 30 450 3 50 100 600 750 10 20 TYP MAX 0.7 UNITS V
AS29372
A
Regulator Output Current in (note 8) Shutdown
A
NOTES: 1. Unless otherwise specified, VIN = VOUT = 1V, IL = 5mA, CL = 10F, 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. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
3
oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc.
AS29372
SCHEMATIC DIAGRAM
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc.
AS29372
TYPICAL CHARACTERISTICS
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
5
oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc.
AS29372
TYPICAL CHARACTERISTICS (Cont.)
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
6
oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc. APPLICATIONS INFORMATION
External Capacitors
A 10F (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 -30C, so solid tantalums are recommended for operation below -25C. The important parameters of the capacitor are an effective series resistance of about 5 or less and a resonant frequency above 500kHz. The value of this capacitor may be increased without limit. At lower values of output current, less output capacitance is required for output stability. The capacitor can be reduced to 0.5F for current below 10mA or 0.15F 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 22F (or greater) capacitor should be used.
AS29372
Reducing Output Noise
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 1F to 220F only decreases the noise from 430V to 160VRMS 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 1 2R1 H 200 Hz
or about 0.01F. When doing this, the output capacitor must be increased to 10F to maintain stability. These changes reduce the output noise from 430V to 100VRMS 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 1A forces an upper limit of 1.2M 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 12A. Since the AS29372 typically draws 100A at no load with SHUTDOWN open-circuited, this is a negligible addition.
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
7
oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc.
AS29372
TYPICAL APPLICATIONS
*Minimum INPUT-OUTPUT voltage ranges from 40mV to 400mV, depending on load current.
Figure 1. AS29372 Adjustable Regulator
Figure 2. AS29372 Wide Input Voltage Range Current Limiter
*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. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc. MECHANICAL DEFINITIONS*
Package Designator F
AS29372
*All measurements are in inches. Drawing is not to scale.
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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oltag Re gulator Volta g e Re gulator
Austin Semiconductor, Inc.
AS29372
ORDERING INFORMATION
EXAMPLE:
AS29372F/883
Device Number Package Type Process AS29372 F /*
*AVAILABLE PROCESSES *AVAILABLE PROCESSES IT = Industrial Temperature Range XT = Extended Temperature Range MIL = MIL/883 equivalent processing compliant to paragraph 1.2.2 SPACE= MIL 883 equivalent SPACE Process flow compliant to para 1.2.2
-40oC to +85oC -55oC to +125oC -55oC to +125oC -55oC to +125oC
AS29372 Rev. 2.6 06/05
Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.
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