May 2005
LP2992
Micropower 250 mA Low-Noise Ultra Low-Dropout
Regulator in SOT-23 and LLP Packages
Designed for Use with Very Low ESR Output Capacitors
LP2992 Micropower 250 mA Low-Noise Ultra Low-Dropout Regulator in SOT-23 and LLP
Packages
General Description
The LP2992 is a 250 mA, fixed-output voltage regulator
designed to provide ultra low-dropout and low noise in battery powered applications.
™
Using an optimized VIP
cess, the LP2992 delivers unequalled performance in all
specifications critical to battery-powered designs:
Dropout Voltage: Typically 450 mV
@
5mV
Ground Pin Current: Typically 1500 µA
75 µA
Enhanced Stability: The LP2992 is stable with output ca-
pacitor ESR as low as 5 mΩ, which allows the use of ceramic
capacitors on the output.
Sleep Mode: Less than 1 µA quiescent current when ON/
OFF pin is pulled low.
Smallest Possible Size: SOT-23 and LLP packages use
absolute minimum board space.
Precision Output: 1% tolerance output voltages available
(A grade).
Low Noise: By adding a 10 nF bypass capacitor, output
noise can be reduced to 30 µV (typical).
Multiple voltage options, from 1.5V to 5.0V, are available as
standard products. Consult factory for custom voltages.
1 mA load.
@
1 mA load.
(Vertically Integrated PNP) pro-
@
250 mA load, and
@
250 mA load, and
Features
n Ultra low dropout voltage
n Guaranteed 250 mA output current
n Smallest possible size (SOT-23, LLP package)
n Requires minimum external components
n Stable with low-ESR output capacitor
<
n
1 µA quiescent current when shut down
n Low ground pin current at all loads
n Output voltage accuracy 1% (A Grade)
n High peak current capability
n Wide supply voltage range (16V max)
n Low Z
n Overtemperature/overcurrent protection
n −40˚C to +125˚C junction temperature range
n Custom voltages available
: 0.3Ω typical (10 Hz to 1 MHz)
OUT
Applications
n Cellular Phone
n Palmtop/Laptop Computer
n Personal Digital Assistant (PDA)
n Camcorder, Personal Stereo, Camera
Block Diagram
20029401
VIP™is a trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation DS200294 www.national.com
Basic Application Circuit
LP2992
*ON/OFF input must be actively terminated. Tie to VINif this function is not to be used.
**Minimum capacitance is shown to ensure stability (may be increased without limit). Ceramic capacitor required for output (see Application Hints).
***Reduces output noise (may be omitted if application is not noise critical). Use ceramic or film type with very low leakage current (see Application Hints).
20029402
Connection Diagrams
5-Lead Small Outline Package (M5) 6-Lead LLP Package (LD)
Top View
20029403
See NS Package Number MF05A
For ordering information see Table 1
Top View
See NS Package Number NLDBA006
Outline Drawing LDE06A
20029446
www.national.com 2
Ordering Information
TABLE 1. Package Marking and Ordering Information
Output Voltage
(V)
5-Lead Small Outline Package (M5)
1.5 A LP2992AIM5X-1.5 LFBA 3000 Units on Tape and Reel
1.5 A LP2992AIM5-1.5 LFBA 1000 Units on Tape and Reel
1.5 STD LP2992IM5X-1.5 LFBB 3000 Units on Tape and Reel
1.5 STD LP2992IM5-1.5 LFBB 1000 Units on Tape and Reel
1.8 A LP2992AIM5X-1.8 LFCA 3000 Units on Tape and Reel
1.8 A LP2992AIM5-1.8 LFCA 1000 Units on Tape and Reel
1.8 STD LP2992IM5X-1.8 LFCB 3000 Units on Tape and Reel
1.8 STD LP2992IM5-1.8 LFCB 1000 Units on Tape and Reel
2.5 A LP2992AIM5X-2.5 LFDA 3000 Units on Tape and Reel
2.5 A LP2992AIM5-2.5 LFDA 1000 Units on Tape and Reel
2.5 STD LP2992IM5X-2.5 LFDB 3000 Units on Tape and Reel
2.5 STD LP2992IM5-2.5 LFDB 1000 Units on Tape and Reel
3.0 A LP2992AIM5X-3.0 LF8A 3000 Units on Tape and Reel
3.0 A LP2992AIM5-3.0 LF8A 1000 Units on Tape and Reel
3.0 STD LP2992IM5X-3.0 LF8B 3000 Units on Tape and Reel
3.0 STD LP2992IM5-3.0 LF8B 1000 Units on Tape and Reel
3.3 A LP2992AIM5X-3.3 LFEA 3000 Units on Tape and Reel
3.3 A LP2992AIM5-3.3 LFEA 1000 Units on Tape and Reel
3.3 STD LP2992IM5X-3.3 LFEB 3000 Units on Tape and Reel
3.3 STD LP2992IM5-3.3 LFEB 1000 Units on Tape and Reel
5.0 A LP2992AIM5X-5.0 LFFA 3000 Units on Tape and Reel
5.0 A LP2992AIM5-5.0 LFFA 1000 Units on Tape and Reel
5.0 STD LP2992IM5X-5.0 LFFB 3000 Units on Tape and Reel
5.0 STD LP2992IM5-5.0 LFFB 1000 Units on Tape and Reel
6-Lead LLP Package (LDE06A)
1.5 A LP2992AILDX-1.5 L011A 4500 Units on Tape and Reel
1.5 A LP2992AILD-1.5 L011A 1000 Units on Tape and Reel
1.5 STD LP2992ILDX-1.5 L011AB 4500 Units on Tape and Reel
1.5 STD LP2992ILD-1.5 L011AB 1000 Units on Tape and Reel
1.8 A LP2992AILDX-1.8 L012A 4500 Units on Tape and Reel
1.8 A LP2992AILD-1.8 L012A 1000 Units on Tape and Reel
1.8 STD LP2992ILDX-1.8 L012AB 4500 Units on Tape and Reel
1.8 STD LP2992ILD-1.8 L012AB 1000 Units on Tape and Reel
2.5 A LP2992AILDX-2.5 L013A 4500 Units on Tape and Reel
2.5 A LP2992AILD-2.5 L013A 1000 Units on Tape and Reel
2.5 STD LP2992ILDX-2.5 L013AB 4500 Units on Tape and Reel
2.5 STD LP2992ILD-2.5 L013AB 1000 Units on Tape and Reel
3.3 A LP2992AILDX-3.3 L014A 4500 Units on Tape and Reel
3.3 A LP2992AILD-3.3 L014A 1000 Units on Tape and Reel
3.3 STD LP2992ILDX-3.3 L014AB 4500 Units on Tape and Reel
3.3 STD LP2992ILD-3.3 L014AB 1000 Units on Tape and Reel
5.0 A LP2992AILDX-5.0 L015A 4500 Units on Tape and Reel
5.0 A LP2992AILD-5.0 L015A 1000 Units on Tape and Reel
5.0 STD LP2992ILDX-5.0 L015AB 4500 Units on Tape and Reel
5.0 STD LP2992ILD-5.0 L015AB 1000 Units on Tape and Reel
Grade Order Information
Package
Marking
LP2992
Supplied as:
www.national.com3
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
LP2992
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature Range −65˚C to +150˚C
Input Supply Voltage (Survival) −0.3V to +16V
Input Supply Voltage (Operating) 2.2V to +16V
Shutdown Input Voltage (Survival) −0.3V to +16V
Output Voltage (Survival, (Note 4)) −0.3V to +9V
I
(Survival) Short Circuit
OUT
Operating Junction Temperature
Range −40˚C to +125˚C
Lead Temp. (Soldering, 5 sec.) 260˚C
Input-Output Voltage (Survival, −0.3V to +16V
(Note 5))
ESD Rating (Note 2) 2 kV
Power Dissipation (Note 3) Internally Limited
Electrical Characteristics
Limits in standard typeface are for TJ= 25˚C. and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: V
(NOM) + 1V, IL= 1 mA, CIN= 1 µF, C
IN=VO
Symbol Parameter Conditions Typ
∆V
O
Output Voltage
Tolerance
IL= 1 mA −1.0 1.0 −1.5 1.5
1mA≤ IL≤ 50 mA −1.5 1.5 −2.5 2.5
1mA≤ I
≤ 250 mA −3.5 3.5 −4.0 4.0
L
Output Voltage VO(NOM)+1V ≤ VIN≤ 16V 0.007 0.014 0.014
Line Regulation 0.032 0.032
V
(min) Minimum input voltage
IN
required to maintain
outpout regulation
V
IN–VO
Dropout Voltage
IL= 0 0.5 2.5 2.5
(Note 7)
I
=1mA 5 9 9
L
I
= 50 mA 100 125 125
L
I
= 150 mA 260 325 325
L
I
= 250 mA 450 575 575
L
I
GND
V
ON/OFF
Ground Pin Current IL= 0 65 95 95
= 1 mA 75 110 110
I
L
I
= 50 mA 350 600 600
L
I
= 150 mA 850 1500 1500
L
I
= 250 mA 1500 2300 2300
L
ON/OFF
ON/OFF
<
0.3V 0.01 0.8 0.8
<
0.15V 0.05 2 2
ON/OFF Input Voltage
(Note 8)
V
V
High = O/P ON 1.4 1.6 1.6
Low = O/P OFF 0.55 0.15 0.15
= 4.7 µF, V
OUT
ON/OFF
= 2V.
LP2992AI-X.X LP2992I-X.X
Min Max Min Max
−2.5 2.5 −3.5 3.5
−4.5 4.5 −5.0 5.0
2.05 2.20 2.20 V
44
12 12
180 180
470 470
850 850
125 125
170 170
1000 1000
2500 2500
4000 4000
Protected
Units(Note 6) (Note 6)
%V
NOM
%/V
mV
µA
V
www.national.com 4
Electrical Characteristics (Continued)
Limits in standard typeface are for TJ= 25˚C. and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: V
(NOM) + 1V, IL= 1 mA, CIN= 1 µF, C
IN=VO
Symbol Parameter Conditions Typ
I
ON/OFF
e
n
(SC) Short Circuit Current RL= 0 (Steady State)
I
O
ON/OFF Input Current V
V
= 0 0.01 −2 −2
ON/OFF
=5V 5 15 15
ON/OFF
Output Noise BW = 300 Hz to 50 kHz,
Voltage (RMS) C
Ripple Rejection f = 1 kHz, C
=10µF 30 µV
OUT
C
C
BYPASS
OUT
=10nF
BYPASS
=10µF
=10nF
(Note 9)
I
(PK) Peak Output Current V
O
Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the
device outside of its rated operating conditions.
Note 2: The ESD rating of pins 3 and 4 for the SOT-23 package, or pins 1 and 3 for the LLP package, is 1 kV.
Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, T
and the ambient temperature, T
. The maximum allowable power dissipation at any ambient temperture is calculated using:
A
≥ Vo(NOM) −5% 350 mA
OUT
= 4.7 µF, V
OUT
ON/OFF
= 2V.
LP2992AI-X.X LP2992I-X.X
Min Max Min Max
45 dB
400 mA
(MAX), the junction-to-ambient thermal resistance, θ
J
LP2992
Units(Note 6) (Note 6)
µA
,
J-A
Where the value of θ
dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown.
Note 4: If used in a dual-supply system where the regulator load is returned to a negative supply, the LP2992 output must be diode-clamped to ground.
Note 5: The output PNP structure contains a diode between the V
turn on this diode.
Note 6: Limits are 100% production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National’s Average Outgoing Quality Level (AOQL).
Note 7: V
at which the output voltage drops 2% below the value measured with a 1V differential.
Note 8: The ON/OFF input must be properly driven to prevent possible misoperation. For details, refer to Application Hints.
Note 9: The LP2992 has foldback current limiting which allows a high peak current when V
forced to ground (see Typical Performance Characteristics curves).
must be the greater of 2.2V or V
IN
for the SOT-23 package is 220˚C/W in a typical PC board mounting and the LLP package is 65˚C/W. Exceeding the maximum allowable
J-A
to V
IN
+ Dropout Voltage to maintain output regulation. Dropout voltage is defined as the input to output differential
OUT(nom)
terminals that is normally reverse-biased. Reversing the polarity from VINto V
OUT
>
0.5V, and then reduces the maximum output current as V
OUT
OUT
will
OUT
is
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Typical Performance Characteristics Unless otherwise specified: C
(NOM) +1, TA= 25˚C, ON/OFF pin is tied to VIN.
V
OUT
LP2992
vs Temperature Short-Circuit Current
V
OUT
20029408
Short-Circuit Current Short Circuit Current vs Output Voltage
= 1µF, C
IN
= 4.7µF, VIN=
OUT
20029409
20029410
Ripple Rejection Ripple Rejection
20029413 20029414
20029411
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LP2992
Typical Performance Characteristics Unless otherwise specified: C
(NOM) +1, TA= 25˚C, ON/OFF pin is tied to VIN. (Continued)
V
OUT
Ripple Rejection Ripple Rejection
20029415 20029416
Ripple Rejection Ripple Rejection
= 1µF, C
IN
= 4.7µF, VIN=
OUT
20029417 20029418
Ripple Rejection Ripple Rejection
20029419 20029423
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Typical Performance Characteristics Unless otherwise specified: C
(NOM) +1, TA= 25˚C, ON/OFF pin is tied to VIN. (Continued)
V
OUT
LP2992
Ripple Rejection Output Impedance vs Frequency
= 1µF, C
IN
= 4.7µF, VIN=
OUT
20029422
Output Impedance vs Frequency Output Noise Density
20029421
Output Noise Density GND Pin vs Load Current
20029420
20029424
20029425
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20029426
LP2992
Typical Performance Characteristics Unless otherwise specified: C
(NOM) +1, TA= 25˚C, ON/OFF pin is tied to VIN. (Continued)
V
OUT
Dropout Voltage vs Temperature Input Current vs Pin
20029427
Ignd vs Load and Temperature Instantaneous Short Circuit Current
= 1µF, C
IN
= 4.7µF, VIN=
OUT
20029429
20029430
Load Transient Response Load Transient Response
20029433
20029431
20029434
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Typical Performance Characteristics Unless otherwise specified: C
(NOM) +1, TA= 25˚C, ON/OFF pin is tied to VIN. (Continued)
V
OUT
LP2992
Load Transient Response Line Transient Response
= 1µF, C
IN
= 4.7µF, VIN=
OUT
20029447
Line Transient Response Line Transient Response
20029436
Line Transient Response Turn-On Time
20029435
20029437
20029438 20029439
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LP2992
Typical Performance Characteristics Unless otherwise specified: C
(NOM) +1, TA= 25˚C, ON/OFF pin is tied to VIN. (Continued)
V
OUT
Turn-On Time Turn-On Time
20029440
Turn-On Time
= 1µF, C
IN
= 4.7µF, VIN=
OUT
20029441
20029442
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Application Hints
LP2992
EXTERNAL CAPACITORS
Like any low-dropout regulator, the LP2992 requires external
capacitors for regulator stability. These capacitors must be
correctly selected for good performance.
Input Capacitor
An input capacitor whose capacitance is ≥ 1 µF is required
between the LP2992 input and ground (the amount of capacitance may be increased without limit).
This capacitor must be located a distance of not more than 1
cm from the input pin and returned to a clean analog ground.
Any good quality ceramic, tantalum, or film capacitor may be
used at the input.
Important: Tantalum capacitors can suffer catastrophic failure due to surge current when connected to a lowimpedance source of power (like a battery or 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 ESR on the input capacitor,
but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance
will be ≥ 1 µF over the entire operating temperature range.
Output Capacitor:
The LP2992 is designed specifically to work with ceramic
output capacitors, utilizing circuitry which allows the regulator to be stable across the entire range of output current with
an output capacitor whose ESR is as low as 5 mΩ.Itmay
also be possible to use Tantalum or film capacitors at the
output, but these are not as attractive for reasons of size and
cost (see next section Capacitor Characteristics).
The output capacitor must meet the requirement for minimum amount of capacitance and also have an ESR (equivalent series resistance) value which is within the stable range.
Curves are provided which show the stable ESR range as a
function of load current (see ESR graph below).
20029407
Important: The output capacitor must maintain its ESR
within the stable region over the full operating temperature
range of the application to assure stability.
The LP2992 requires a minimum of 4.7 µF on the output
(output capacitor size can be increased without limit).
It is important to remember that capacitor tolerance and
variation with temperature must be taken into consideration
when selecting an output capacitor so that the minimum
required amount of output capacitance is provided over the
full operating temperature range. It should be noted that
ceramic capacitors can exhibit large changes in capacitance
with temperature (see next section, Capacitor Characteris-
tics).
The output capacitor must be located not more than 1 cm
from the output pin and returned to a clean analog ground.
Noise Bypass Capacitor:
Connecting a 10 nF capacitor to the Bypass pin significantly
reduces noise on the regulator output. It should be noted that
the capacitor is connected directly to a high-impedance circuit in the bandgap reference.
Because this circuit has only a few microamperes flowing in
it, any significant loading on this node will cause a change in
the regulated output voltage. For this reason, DC leakage
current through the noise bypass capacitor must never exceed 100 nA, and should be kept as low as possible for best
output voltage accuracy.
The types of capacitors best suited for the noise bypass
capacitor are ceramic and film. High-quality ceramic capacitors with either NPO or COG dielectric typically have very
low leakage. 10 nF polypropolene and polycarbonate film
capacitors are available in small surface-mount packages
and typically have extremely low leakage current.
CAPACITOR CHARACTERISTICS
The LP2992 was designed to work with ceramic capacitors
on the output to take advantage of the benefits they offer: for
capacitance values in the 2.2 µF to 10 µF range, ceramics
are the least expensive and also have the lowest ESR
values (which makes them best for eliminating highfrequency noise). The ESR of a typical 4.7 µF ceramic
capacitor is in the range of 5 mΩ to 10 mΩ, which easily
meets the ESR limits required for stability by the LP2992.
One disadvantage of ceramic capacitors is that their capacitance can vary with temperature. Most large value ceramic
capacitors (≥ 2.2 µF) are manufactured with the Z5U or Y5V
temperature characteristic, which results in the capacitance
dropping by more than 50% as the temperature goes from
25˚C to 85˚C.
This could cause problems if a 4.7 µF capacitor were used
on the output since it will drop down to approximately 2.3 µF
at high ambient temperatures (which could cause the
LP2992 to oscillate). If Z5U or Y5V capacitors are used on
the output, a minimum capacitance value of 10 µF must be
observed.
A better choice for temperature coefficient in ceramic capacitors is X7R, which holds the capacitance within
fortunately, the larger values of capacitance are not offered
by all manufacturers in the X7R dielectric.
Tantalum:
Tantalum capacitors are less desirable than ceramics for use
as output capacitors because they are more expensive when
comparing equivalent capacitance and voltage ratings in the
1 µF to 4.7 µF 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.
±
15%. Un-
www.national.com 12
Application Hints (Continued)
It should also be noted that the ESR of a typical Tantalum will
increase about 2:1 as the temperature goes from 25˚C down
to −40˚C, so some guard band must be allowed.
ON/OFF INPUT OPERATION
The LP2992 is shut off by driving the ON/OFF input low, and
turned on by pulling it high. If this feature is not to be used,
the ON/OFF input should be tied to V
output on at all times.
To assure proper operation, the signal source used to drive
the ON/OFF input must be able to swing above and below
the specified turn-on/turn-off voltage thresholds listed in the
Electrical Characteristics section under V
mis-operation, the turn-on (and turn-off) voltage signals applied to the ON/OFF input must have a slew rate which is
≥ 40 mV/µs.
Caution: the regulator output voltage can not be guaranteed
if a slow-moving AC (or DC) signal is applied that is in the
range between the specified turn-on and turn-off voltages
listed under the electrical specification V
cal Characteristics).
REVERSE INPUT-OUTPUT VOLTAGE
The PNP power transistor used as the pass element in the
LP2992 has an inherent diode connected between the regulator output and input. During normal operation (where the
input voltage is higher than the output) this diode is reversebiased.
to keep the regulator
IN
. To prevent
ON/OFF
(see Electri-
ON/OFF
However, if the output is pulled above the input, this diode
will turn ON and current will flow into the regulator output. In
such cases, a parasitic SCR can latch which will allow a high
current to flow into V
(and out the ground pin), which can
IN
damage the part.
In any application where the output may be pulled above the
input, an external Schottky diode must be connected from
to V
V
IN
(cathode on VIN, anode on V
OUT
), to limit the
OUT
reverse voltage across the LP2992 to 0.3V (see Absolute
Maximum Ratings).
LLP MOUNTING
The LLP package requires specific mounting techniques
which are detailed in National Semiconductor Application
Note # 1187. Referring to the section PCB Design Recom-
mendations, it should be noted that the pad style which
should be used with the LLP package is the NSMD (nonsolder mask defined) type.
LP2992
www.national.com13
Physical Dimensions inches (millimeters)
unless otherwise noted
LP2992
5-Lead Small Outline Package (M5)
NS Package Number MF05A
For Order Numbers, refer to Table 1 in the “Ordering Information” section of this document.
www.national.com 14
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
LP2992 Micropower 250 mA Low-Noise Ultra Low-Dropout Regulator in SOT-23 and LLP
Packages
6-Lead LLP Package (LD)
NS Package Number LDE06A
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
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which, (a) are intended for surgical implant into the body, or
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2. A critical component is any component of a life support
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provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
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