SM72238
SM72238 SolarMagic Micropower Voltage Regulator
Literature Number: SNVS694B
SM72238
May 9, 2011
SolarMagic Micropower Voltage Regulator
General Description
The SM72238 is a micropower voltage regulator with very low
quiescent current (75μA typ.) and very low dropout voltage
(typ. 40mV at light loads and 380mV at 100mA). It is ideally
suited for use in battery-powered systems. Furthermore, the
quiescent current of the SM72238 increases only slightly in
dropout, prolonging battery life.
The SM72238 is available in the surface-mount D-Pak pack-
age.
Careful design of the SM72238 has minimized all contribu-
tions to the error budget. This includes a tight initial tolerance
(.5% typ.), extremely good load and line regulation (.05% typ.)
and a very low output voltage temperature coefficient, making
the part useful as a low-power voltage reference.
Features
■Renewable Energy Grade
■High accuracy output voltage
■Guaranteed 100mA output current
■Extremely low quiescent current
■Low dropout voltage
■Extremely tight load and line regulation
■Very low temperature coefficient
■Use as Regulator or Reference
■Needs minimum capacitance for stability
■Current and Thermal Limiting
■Stable with low-ESR output capacitors (10mΩ to 6Ω)
Block Diagram and Typical Applications
SM72238
30141325
© 2011 National Semiconductor Corporation 301413 www.national.com
SM72238 SolarMagic Micropower Voltage Regulators
Connection Diagrams
TO-252 (D-Pak)
30141370
Front View
Ordering Information
Package Temperature
Range VOUT Part Number Package Marking Transport Media NSC Drawing
TO-252
(DPAK) -40<TJ<125 3.0
SM72238TD-3.0
S72238–3.0
75 Units in Rail
TD03BSM72238TDE-3.0 250 Units in Tape and Reel
SM72238TDX-3.0 2500 Units in Tape and Reel
TO-252
(DPAK) -40<TJ<125 3.3
SM72238TD-3.3
S72238–3.3
75 Units in Rail
TD03BSM72238TDE-3.3 250 Units in Tape and Reel
SM72238TDX-3.3 2500 Units in Tape and Reel
TO-252
(DPAK) -40<TJ<125 5.0
SM72238TD-5.0
S72238
75 Units in Rail
TD03BSM72238TDE-5.0 250 Units in Tape and Reel
SM72238TDX-5.0 2500 Units in Tape and Reel
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SM72238
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Supply Voltage −0.3 to +30V
Power Dissipation Internally Limited
Junction Temperature (TJ)+150°C
Ambient Storage Temperature −65° to +150°C
Soldering Dwell Time, Temperature
Wave
Infrared
Vapor Phase
4 seconds, 260°C
10 seconds, 240°C
75 seconds, 219°C
ESD Rating
Human Body Model(Note 11) 2500V
Operating Ratings (Note 1)
Maximum Input Supply Voltage 30V
Junction Temperature Range
(TJ) (Note 6)−40° to +125°C
Electrical Characteristics (Note 2)
Parameter Conditions (Note 2)Typ Tested Limit (Note 3)Design Limit (Note 4)Units
3V Versions
Output Voltage TJ = 25°C 3.0 3.030 V max
2.970 V min
−25°C ≤ TJ ≤ 85°C 3.0 3.045 V max
2.955 V min
Full Operating 3.0 3.060 V max
Temperature Range 2.940 V min
Output Voltage 100μA ≤ IL ≤ 100mA 3.0 3.072 V max
TJ ≤ TJMAX 2.928 V min
3.3V Versions
Output Voltage TJ = 25°C 3.3 3.333 V max
3.267 V min
−25°C ≤ TJ ≤ 85°C 3.3 3.350 V max
3.251 V min
Full Operating 3.3 3.366 V max
Temperature Range 3.234 V min
Output Voltage 100μA ≤ IL ≤ 100mA 3.3 3.379 V max
TJ ≤ TJMAX 3.221 V min
5.0V Versions
Output Voltage TJ = 25°C 5.0 5.05 V max
4.95 V min
−25°C ≤ TJ ≤ 85°C 5.0 5.075 V max
4.925 V min
Full Operating 5.0 5.1 V max
Temperature Range 4.9 V min
Output Voltage 100μA ≤ IL ≤ 100mA 5.0 5.12 V max
TJ ≤ TJMAX 4.88 V min
All Voltage Options
Output Voltage
Temperature Coefficient
(Note 7)50 150 ppm/°C
Line Regulation
(Note 9)
(VONOM + 1)V ≤ Vin ≤ 30V (Note
10)
0.04 0.2 % max
0.4 % max
Load Regulation
(Note 9)
100μA ≤ IL ≤ 100mA 0.1 0.2 % max
0.3 % max
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SM72238
Parameter Conditions (Note 2)Typ Tested Limit (Note 3)Design Limit (Note 4)Units
Dropout Voltage
(Note 5)
IL = 100μA 80 mV max
50 150 mV max
IL = 100mA 450 mV max
380 600 mV max
Ground IL = 100μA75 120 μA max
Current 140 μA max
IL = 100mA 8 12 mA max
14 mA max
Dropout Vin = (VONOM − 0.5)V 110 170 μA max
Ground Current IL = 100μA 200 μA max
Current Limit Vout = 0 160 200 mA max
220 mA max
Thermal Regulation (Note 8) 0.05 0.2 %/W
max
Output Noise, CL = 1μF (5V Only) 430 μV rms
10 Hz to 100 kHz CL = 200μF160 μV rms
CL = 3.3μF
(Bypass = 0.01μF) 100 μV rms
Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the
device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the
Electrical Characteristics tables.
Note 2: Unless otherwise specified all limits guaranteed for VIN = (VONOM + 1)V, IL = 100μA and CL = 1μF. Limits appearing in boldface type apply over the entire
junction temperature range for operation. Limits appearing in normal type apply for TA = TJ = 25°C.
Note 3: Guaranteed and 100% production tested.
Note 4: Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels.
Note 5: Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V differential.
At very low values of programmed output voltage, the minimum input supply voltage of 2V (2.3V over temperature) must be taken into account.
Note 6: Junction-to-case thermal resistance for the TO-252 package is 5.4°C/W.
Note 7: Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 8: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation
effects. Specifications are for a 50mA load pulse at VIN = 30V (1.25W pulse) for T = 10ms.
Note 9: Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating effects are
covered under the specification for thermal regulation.
Note 10: For IL = 100μA and TJ = 125°C, line regulation is guaranteed by design to 0.2%. See Typical Performance Characteristics for line regulation versus
temperature and load current.
Note 11: Human Body Model 1.5kΩ in series with 100pF.
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SM72238
Typical Performance Characteristics
Quiescent Current
30141327
Dropout Characteristics
30141328
Input Current
30141329
Input Current
30141330
Output Voltage vs. Temperature of 3
Representative Units
30141331
Quiescent Current
30141332
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SM72238
Quiescent Current
30141333
Quiescent Current
30141334
Quiescent Current
30141335
Short Circuit Current
30141336
Dropout Voltage
30141337
Line Transient Response
30141344
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SM72238
Load Transient Response
30141345
Load Transient Response
30141346
Output Impedance
30141348
Ripple Rejection
30141349
Ripple Rejection
30141350
Ripple Rejection
30141351
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SM72238
Shutdown Threshold Voltage
30141354
Line Regulation
30141355
Maximum Rated Output Current
30141357
Thermal Response
30141358
Output Capacitor ESR Range
30141363
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SM72238
Application Hints
EXTERNAL CAPACITORS
A 1.0μF (or greater) capacitor is required between the output
and ground for stability. Without this capacitor the part will
oscillate. Most types of tantalum or aluminum electrolytics
work fine here; even film types work but are not recommended
for reasons of cost. Many aluminum electrolytics have elec-
trolytes that freeze at about −30°C, so solid tantalums are
recommended for operation below −25°C. The important pa-
rameters of the capacitor are an ESR of about 5Ω or less and
a resonant frequency above 500kHz. The value of this ca-
pacitor may be increased without limit.
Ceramic capacitors whose value is greater than 1000pF
should not be connected directly from the SM72238 output to
ground. Ceramic capacitors typically have ESR values in the
range of 5 to 10mΩ, a value below the lower limit for stable
operation (see curve Output Capacitor ESR Range).
The reason for the lower ESR limit is that the loop compen-
sation of the part relies on the ESR of the output capacitor to
provide the zero that gives added phase lead. The ESR of
ceramic capacitors is so low that this phase lead does not
occur, significantly reducing phase margin. A ceramic output
capacitor can be used if a series resistance is added (recom-
mended value of resistance about 0.1Ω to 2Ω).
At lower values of output current, less output capacitance is
required for stability. The capacitor can be reduced to
0.33μF for currents below 10mA or 0.1μF for currents below
1mA.
Unlike many other regulators, the SM72238 will remain stable
and in regulation with no load in addition to the internal voltage
divider. This is especially important in CMOS RAM keep-alive
applications.
A 1μF tantalum, ceramic or aluminum electrolytic capacitor
should be placed from the SM72238 input to ground if there
is more than 10 inches of wire between the input and the AC
filter capacitor or if a battery is used as the input.
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 the only way noise can be reduced but is
relatively inefficient, as increasing the capacitor from 1μF to
220μF only decreases the noise from 430μV to 160μV rms for
a 100kHz bandwidth at 5V output.
Typical Applications
5 Volt Current Limiter
30141310
*Minimum input-output voltage ranges from 40mV to 400mV, depending on load current. Current limit is typically 160mA.
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SM72238
Schematic Diagram
30141323
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SM72238
Physical Dimensions inches (millimeters) unless otherwise noted
D-Pak Package
NS Package Number TD03B
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SM72238
Notes
SM72238 SolarMagic Micropower Voltage Regulators
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