LP3990
150mA Linear Voltage Regulator for Digital Applications
General Description
The LP3990 regulator is designed to meet the requirements
of portable, battery-powered systems providing an accurate
output voltage, low noise, and low quiescent current. The
LP3990 will provide a 0.8V output from the low input voltage
of 2V at up to 150mA load current. When switched into
shutdown mode via a logic signal at the enable pin, the
power consumption is reduced to virtually zero.
The LP3990 is designed to be stable with space saving
ceramic capacitors as small as 1.0µF.
Performance is specified for a -40˚C to 125˚C junction tem-
perature range.
For output voltages other than 0.8V, 1.35V, 1.5V, 1.8V, 2.5V,
2.8V, or 3.3V please contact your local NSC sales office.
Features
n1% Voltage Accuracy at Room Temperature
nStable with Ceramic Capacitor
nLogic Controlled Enable
nNo Noise Bypass Capacitor Required
nThermal-Overload and Short-Circuit Protection
Key Specifications
nInput Voltage Range 2.0 to 6.0V
nOutput Voltage Range 0.8 to 3.3V
nOutput Current 150mA
nOutput Stable - Capacitors 1.0uF
nVirtually Zero I
Q
(Disabled) <10nA
nVery Low I
Q
(Enabled) 43uA
nLow Output Noise 150uV
RMS
nPSRR 55dB at 1kHz
nFast Start Up 105us
Package
All available in Lead Free option.
4 Pin micro SMD 1 mm x 1.28mm
6 pin LLP (SOT23 footprint)
SOT23 - 5
For other package options contact your NSC sales office.
Applications
nCellular Handsets
nHand-Held Information Appliances
Typical Application Circuit
20076801
February 2005
LP3990 150mA Linear Voltage Regulator for Digital Applications
© 2005 National Semiconductor Corporation DS200768 www.national.com
Pin Descriptions
Packages
Pin No Symbol Name and Function
LLP
micro
SMD SOT23-5
5A23 V
EN
Enable Input; Enables the Regulator when ≥0.95V.
Disables the Regulator when ≤0.4V.
Enable Input has 1MΩpulldown resistor to GND.
2 A1 2 GND Common Ground. Connect to Pad.
1B15 V
OUT
Voltage output. A 1.0µF Low ESR Capacitor should be
connected to this Pin. Connect this output to the load circuit.
6B21 V
IN
Voltage Supply Input. A 1.0µF capacitor should be connected
at this input.
3 4 N/C No Connection. Do not connect to any other pin.
4 N/C No Connection. Do not connect to any other pin.
Pad GND Common Ground. Connect to Pin 2.
Connection Diagrams
Micro SMD, 4 Bump Package
20076803
See NS package number TLA04
LLP-6 Package
20076806
See NS package number SDE06A
LP3990
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Connection Diagrams (Continued)
SOT23 - 5 Package (MF)
20076808
See NS package number MF05A
LP3990
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Ordering Information
For micro SMD Package
* Please contact Sales Office for Availability
Output
Voltage (V) Grade LP3990 Supplied as 250
Units, Tape and Reel
LP3990 Supplied as 3000
Units, Tape and Reel Package Marking
0.8 STD LP3990TL-0.8 LP3990TLX-0.8
1.2 STD LP3990TL-1.2 LP3990TLX-1.2
1.35 STD LP3990TL-1.35 LP3990TLX-1.35
1.5 STD LP3990TL-1.5 LP3990TLX-1.5
1.8 STD LP3990TL-1.8 LP3990TLX-1.8
2.5 STD LP3990TL-2.5 LP3990TLX-2.5
2.8 STD LP3990TL-2.8 LP3990TLX-2.8
3.3* STD LP3990TL-3.3 LP3990TLX-3.3
For LLP-6 Package
* Please contact Sales Office for Availability
Output
Voltage (V) Grade LP3990 Supplied as 1000
Units, Tape and Reel
LP3990 Supplied as 3000
Units, Tape and Reel Package Marking
0.8 STD LP3990SD-0.8 LP3990SDX-0.8 L085B
1.2* STD LP3990SD-1.2 LP3990SDX-1.2 L086B
1.35* STD LP3990SD-1.35 LP3990SDX-1.35 L150B
1.5 STD LP3990SD-1.5 LP3990SDX-1.5 L087B
1.8 STD LP3990SD-1.8 LP3990SDX-1.8 L088B
2.5 STD LP3990SD-2.5 LP3990SDX-2.5 L090B
2.8 STD LP3990SD-2.8 LP3990SDX-2.8 L091B
3.3* STD LP3990SD-3.3 LP3990SDX-3.3 L092B
For SOT23 - 5 Package
* Please contact Sales Office for Availability
Output
Voltage (V) Grade LP3990 Supplied as 1000
Units, Tape and Reel
LP3990 Supplied as 3000
Units, Tape and Reel Package Marking
0.8* STD LP3990MF-0.8 LP3990MFX-0.8 SCCB
1.2* STD LP3990MF-1.2 LP3990MFX-1.2 SCDB
1.35* STD LP3990MF-1.35 LP3990MFX-1.35 SHRB
1.5* STD LP3990MF-1.5 LP3990MFX-1.5 SCEB
1.8* STD LP3990MF-1.8 LP3990MFX-1.8 SCFB
2.5* STD LP3990MF-2.5 LP3990MFX-2.5 SCJB
2.8* STD LP3990MF-2.8 LP3990MFX-2.8 SCKB
3.3* STD LP3990MF-3.3 LP3990MFX-3.3 SCLB
LP3990
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Absolute Maximum Ratings
(Notes 1, 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Voltage -0.3 to 6.5V
Output Voltage -0.3 to (V
IN
+ 0.3V) to
6.5V (max)
Enable Input Voltage -0.3 to (V
IN
+ 0.3V) to
6.5V (max)
Junction Temperature 150˚C
Lead/Pad Temp. (Note 3)
LLP/SOT23 235˚C
micro SMD 260˚C
Storage Temperature -65 to 150˚C
Continuous Power Dissipation
Internally Limited(Note 4)
ESD (Note 5)
Human Body Model 2KV
Machine Model 200V
Operating Ratings(Note 1)
Input Voltage 2V to 6V
Enable Input Voltage 0 to (V
IN
+ 0.3V) to
6.0V (max)
Junction Temperature -40˚C to 125˚C
Ambient Temperature T
A
Range
(Note 6)
-40˚C to 85˚C
Thermal Properties(Note 1)
Junction To Ambient Thermal
Resistance(Note 8)
θ
JA
(LLP-6) 88˚C/W
θ
JA
(microSMD) 220˚C/W
θ
JA
SOT23-5 220˚C/W
Electrical Characteristics
Unless otherwise noted, V
EN
=950mV, V
IN
=V
OUT
+ 1.0V, or 2.0V, whichever is higher. C
IN
= 1 µF, I
OUT
= 1 mA, C
OUT
=0.47
µF. Typical values and limits appearing in normal type apply for T
J
= 27˚C. Limits appearing in boldface type apply over the
full junction temperature range for operation, −40 to +125˚C. (Note 13)
Symbol Parameter Conditions Typ Limit Units
Min Max
V
IN
Input Voltage (Note 14) 2 6 V
∆V
OUT
Output Voltage Tolerance I
LOAD
= 1 mA Micro SMD -1 +1
%
LLP -1.5 +1.5
Over full line
and load
regulation.
Micro SMD -2.5 +2.5
LLP -3 +3
Line Regulation Error V
IN
=(V
OUT(NOM)
+ 1.0V) to 6.0V, 0.02 -0.1 0.1 %/V
Load Regulation Error I
OUT
= 1mA
to 150mA
V
OUT
= 0.8 to 1.95V
MicroSMD
0.002 -0.005 0.005
%/mA
V
OUT
= 0.8 to 1.95V
LLP, SOT-23
0.003 -0.008 0.008
V
OUT
= 2.0 to 3.3V
MicroSMD
0.0005 -0.002 0.002
V
OUT
= 2.0 to 3.3V
LLP, SOT-23
0.002 -0.005 0.005
V
DO
Dropout Voltage I
OUT
= 150mA
(Note 7)
120 mV
I
LOAD
Load Current (Notes 9, 10) 0 µA
I
Q
Quiescent Current V
EN
= 950mV, I
OUT
= 0mA 43 80
µAV
EN
= 950mV, I
OUT
= 150mA 65 120
V
EN
= 0.4V 0.002 0.2
I
SC
Short Circuit Current Limit (Note 11) 550 1000 mA
I
OUT
Maximum Output Current 150 mA
PSRR Power Supply Rejection Ratio f = 1kHz, I
OUT
= 1mA to 150mA 55 dB
f = 10kHz, I
OUT
= 150mA 35
LP3990
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Electrical Characteristics (Continued)
Unless otherwise noted, V
EN
=950mV, V
IN
=V
OUT
+ 1.0V, or 2.0V, whichever is higher. C
IN
= 1 µF, I
OUT
= 1 mA, C
OUT
=0.47
µF. Typical values and limits appearing in normal type apply for T
J
= 27˚C. Limits appearing in boldface type apply over the
full junction temperature range for operation, −40 to +125˚C. (Note 13)
Symbol Parameter Conditions Typ Limit Units
Min Max
e
n
Output noise Voltage (Note 10) BW = 10Hz to
100kHz,
V
OUT
= 0.8 60
µV
RMS
V
OUT
= 1.5 125
V
OUT
= 3.3 180
T
SHUTDOWN
Thermal Shutdown Temperature 155 ˚C
Hysteresis 15
Enable Control Characteristics
I
EN
(Note 12)
Maximum Input Current at
V
EN
Input
V
EN
= 0.0V 0.001 0.1 µA
V
EN
=6V 6 2.5 10
V
IL
Low Input Threshold V
IN
=2Vto6V 0.4 V
V
IH
High Input Threshold V
IN
=2Vto6V 0.95 V
Timing Characteristics
T
ON
Turn On Time (Note 10) To 95% Level
V
IN(MIN)
to 6.0V
V
OUT
= 0.8 80 150
µsV
OUT
= 1.5 105 200
V
OUT
= 3.3 175 250
Transient
Response
Line Transient Response |δV
OUT
|T
rise
=T
fall
= 30µs (Note 10)
δV
IN
= 600mV 816 mV
(pk - pk)
Load Transient Response
|δV
OUT
|
T
rise
=T
fall
= 1µs (Note 10)I
OUT
= 1mA
to 150mA
C
OUT
= 1µF
55 100 mV
Note 1: Absolute Maximum Ratings are limits beyond which damage can 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: All Voltages are with respect to the potential at the GND pin.
Note 3: For further information on these packages please refer to the following application notes;AN-1112 Micro SMD Package Wafer Level Chip Scale
Package,AN-1187 Leadless Leadframe Package.
Note 4: Internal thermal shutdown circuitry protects the device from permanent damage.
Note 5: The human body model is 100pF discharged through a 1.5kΩresistor into each pin. The machine model is a 200pF capacitor discharged directly into each
pin.
Note 6: The maximum ambient temperature (TA(max)) is dependant on the maximum operating junction temperature (TJ(max-op) = 125˚C), the maximum power
dissipation of the device in the application (PD(max)), and the junction to ambient thermal resistance of the part/package in the application (θJA), as given by the
following equation: TA(max) =T
J(max-op) -(θJA xP
D(max)).
Note 7: Dropout voltage is voltage difference between input and output at which the output voltage drops to 100mV below its nominal value. This parameter only
for output voltages above 2.0V.
Note 8: Junction to ambient thermal resistance is dependant on the application and board layout. In applications where high maximum power dissipation is possible,
special care must be paid to thermal dissipation issues in board design.
Note 9: The device maintains the regulated output voltage without the load.
Note 10: This electrical specification is guaranteed by design.
Note 11: Short circuit current is measured with VOUT pulled to 0V and VIN worst case = 6.0V.
Note 12: Enable Pin has 1MΩtypical, resistor connected to GND.
Note 13: All limits are guaranteed. All electrical characteristics having room-temperature limits are tested during production at TJ= 25˚C or correlated using
Statistical Quality Control methods. Operation over the temperature specification is guaranteed by correlating the electrical characteristics to process and
temperature variations and applying statistical process control.
Note 14: VIN(MIN) =V
OUT(NOM) + 0.5V, or 2.0V, whichever is higher.
Output Capacitor, Recommended Specifications
Symbol Parameter Conditions Nom Limit Units
Min Max
C
OUT
Output Capacitance Capacitance
(Note 15)
1.0 0.7 µF
ESR 5 500 mΩ
LP3990
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Output Capacitor, Recommended Specifications (Continued)
Note 15: The full operating conditions for the application should be considered when selecting a suitable capacitor to ensure that the minimum value of capacitance
is always met. Recommended capacitor type is X7R. However, dependent on application, X5R, Y5V, and Z5U can also be used. (See capacitor section in
Applications Hints)
Typical Performance Characteristics. Unless otherwise specified, C
IN
= 1.0µF Ceramic, C
OUT
=
0.47 µF Ceramic, V
IN
=V
OUT(NOM)
+ 1.0V, T
A
= 25˚C, V
OUT(NOM)
= 1.5V , Shutdown pin is tied to V
IN
.
Output Voltage Change vs Temperature Ground Current vs Load Current
20076810 20076831
Ground Current vs V
IN
.I
LOAD
= 0mA Ground Current vs V
IN
.I
LOAD
= 1mA
20076812 20076813
LP3990
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Typical Performance Characteristics. Unless otherwise specified, C
IN
= 1.0µF Ceramic, C
OUT
=
0.47 µF Ceramic, V
IN
=V
OUT(NOM)
+ 1.0V, T
A
= 25˚C, V
OUT(NOM)
= 1.5V , Shutdown pin is tied to V
IN
. (Continued)
Ground Current vs V
IN
.I
LOAD
= 150mA Short Circuit Current
20076814
20076815
Short Circuit Current Line transient
20076816 20076817
Power Supply Rejection Ratio Power Supply Rejection Ratio
20076819 20076820
LP3990
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Typical Performance Characteristics. Unless otherwise specified, C
IN
= 1.0µF Ceramic, C
OUT
=
0.47 µF Ceramic, V
IN
=V
OUT(NOM)
+ 1.0V, T
A
= 25˚C, V
OUT(NOM)
= 1.5V , Shutdown pin is tied to V
IN
. (Continued)
Enable Start-up Time Enable Start-up Time
20076821 20076822
Load Transient Noise Density
20076825
20076828
LP3990
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Application Hints
EXTERNAL CAPACITORS
In common with most regulators, the LP3990 requires exter-
nal capacitors for regulator stability. The LP3990 is specifi-
cally designed for portable applications requiring minimum
board space and smallest components. These capacitors
must be correctly selected for good performance.
INPUT CAPACITOR
An input capacitor is required for stability. It is recommended
that a 1.0µF capacitor be connected between the LP3990
input pin and ground (this capacitance value may be in-
creased without limit).
This capacitor must be located a distance of not more than
1cm from the input pin and returned to a clean analogue
ground. Any good quality ceramic, tantalum, or film capacitor
may be used at the input.
Important: Tantalum capacitors can suffer catastrophic fail-
ures due to surge current when connected to a low-
impedance source of power (like a battery or a very large
capacitor). If a tantalum capacitor is used at the input, it must
be guaranteed by the manufacturer to have a surge current
rating sufficient for the application.
There are no requirements for the ESR (Equivalent Series
Resistance) on the input capacitor, but tolerance and tem-
perature coefficient must be considered when selecting the
capacitor to ensure the capacitance will remain approxi-
mately 1.0µF over the entire operating temperature range.
OUTPUT CAPACITOR
The LP3990 is designed specifically to work with very small
ceramic output capacitors. A 1.0µF ceramic capacitor (tem-
perature types Z5U, Y5V or X7R) with ESR between 5mΩto
500mΩ, is suitable in the LP3990 application circuit.
For this device the output capacitor should be connected
between the V
OUT
pin and ground.
It is also possible to use tantalum or film capacitors at the
device output, C
OUT
(or V
OUT
), but these are not as attrac-
tive for reasons of size and cost (see the section Capacitor
Characteristics).
The output capacitor must meet the requirement for the
minimum value of capacitance and also have an ESR value
that is within the range 5mΩto 500mΩfor stability.
NO-LOAD STABILITY
The LP3990 will remain stable and in regulation with no
external load. This is an important consideration in some
circuits, for example CMOS RAM keep-alive applications.
CAPACITOR CHARACTERISTICS
The LP3990 is designed to work with ceramic capacitors on
the output to take advantage of the benefits they offer. For
capacitance values in the range of 0.47µF to 4.7µF, ceramic
capacitors are the smallest, least expensive and have the
lowest ESR values, thus making them best for eliminating
high frequency noise. The ESR of a typical 1.0µF ceramic
capacitor is in the range of 20mΩto 40mΩ, which easily
meets the ESR requirement for stability for the LP3990.
For both input and output capacitors, careful interpretation of
the capacitor specification is required to ensure correct de-
vice operation. The capacitor value can change greatly, de-
pending on the operating conditions and capacitor type.
In particular, the output capacitor selection should take ac-
count of all the capacitor parameters, to ensure that the
specification is met within the application. The capacitance
can vary with DC bias conditions as well as temperature and
frequency of operation. Capacitor values will also show
some decrease over time due to aging. The capacitor pa-
rameters are also dependant on the particular case size,
with smaller sizes giving poorer performance figures in gen-
eral. As an example, Figure 1 shows a typical graph com-
paring different capacitor case sizes in a Capacitance vs. DC
Bias plot. As shown in the graph, increasing the DC Bias
condition can result in the capacitance value falling below
the minimum value given in the recommended capacitor
specifications table (0.7µF in this case). Note that the graph
shows the capacitance out of spec for the 0402 case size
capacitor at higher bias voltages. It is therefore recom-
mended that the capacitor manufacturers’ specifications for
the nominal value capacitor are consulted for all conditions,
as some capacitor sizes (e.g. 0402) may not be suitable in
the actual application.
The ceramic capacitor’s capacitance can vary with tempera-
ture. The capacitor type X7R, which operates over a tem-
perature range of -55˚C to +125˚C, will only vary the capaci-
tance to within ±15%. The capacitor type X5R has a similar
tolerance over a reduced temperature range of -55˚C to
+85˚C. Many large value ceramic capacitors, larger than 1µF
are manufactured with Z5U or Y5V temperature characteris-
tics. Their capacitance can drop by more than 50% as the
temperature varies from 25˚C to 85˚C. Therefore X7R is
recommended over Z5U and Y5V in applications where the
ambient temperature will change significantly above or be-
low 25˚C.
Tantalum capacitors are less desirable than ceramic for use
as output capacitors because they are more expensive when
comparing equivalent capacitance and voltage ratings in the
0.47µF to 4.7µF range.
Another important consideration is that tantalum capacitors
have higher ESR values than equivalent size ceramics. This
means that while it may be possible to find a tantalum
capacitor with an ESR value within the stable range, it would
have to be larger in capacitance (which means bigger and
more costly) than a ceramic capacitor with the same ESR
value. It should also be noted that the ESR of a typical
20076840
FIGURE 1. Graph Showing a Typical Variation in
Capacitance vs DC Bias
LP3990
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Application Hints (Continued)
tantalum will increase about 2:1 as the temperature goes
from 25˚C down to -40˚C, so some guard band must be
allowed.
ENABLE CONTROL
The LP3990 features an active high Enable pin, V
EN
, which
turns the device on when pulled high. When not enabled the
regulator output is off and the device typically consumes
2nA.
If the application does not require the Enable switching
feature, the V
EN
pin should be tied to V
IN
to keep the
regulator output permanently on.
To ensure proper operation, the signal source used to drive
the V
EN
input must be able to swing above and below the
specified turn-on/off voltage thresholds listed in the Electrical
Characteristics section under V
IL
and V
IH
.
Micro SMD MOUNTING
The micro SMD package requires specific mounting tech-
niques, which are detailed in National Semiconductor Appli-
cation Note AN-1112.
For best results during assembly, alignment ordinals on the
PC board may be used to facilitate placement of the micro
SMD device.
Micro SMD LIGHT SENSITIVITY
Exposing the micro SMD device to direct light may affect the
operation of the device. Light sources, such as halogen
lamps, can affect electrical performance, if placed in close
proximity to the device.
Light with wavelengths in the infra-red portion of the spec-
trum is the most detrimental, and so, fluorescent lighting
used inside most buildings, has little or no effect on perfor-
mance.
LP3990
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Physical Dimensions inches (millimeters) unless otherwise noted
micro SMD, 4 Bump, Package (TLA04)
NS Package Number TLA04ALA
The dimensions for X1, X2 and X3 are given as:
X1 = 1.003 +/− 0.03mm
X2 = 1.283 +/− 0.03mm
X3 = 0.600 +/− 0.075mm
LLP, 6 Lead, Package (SOT23 Land)
NS Package Number SDE06A
LP3990
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
SOT23 - 5 Package
NS Package Number MF05A
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
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LP3990 150mA Linear Voltage Regulator for Digital Applications
