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LP2989
Micropower/Low Noise, 500 mA Ultra Low-Dropout
Regulator
For Use with Ceramic Output Capacitors
March 2000
LP2989 Micropower/Low Noise, 500 mA Ultra Low-Dropout Regulator
For Use with Ceramic Output Capacitors
General Description
The LP2989 is a fixed-output 500 mA precision LDO regulator designed for use with ceramic output capacitors.
Output noise canbe reduced to 18µV (typical) by connecting
an external 10 nF capacitor to the bypass pin.
Using an optimized VIP
cess, the LP2989 delivers superior performance:
Dropout Voltage: Typically 310 mV
@
mV
100 µA load.
Ground Pin Current: Typically 3 mA
@
110 µA
Sleep Mode: The LP2989 draws less than 0.8 µA quiescent
current when shutdown pin is pulled low.
Error Flag: The built-in error flag goes low when the output
drops approximately 5% below nominal.
Precision Output: Guaranteed output voltage accuracy is
0.75% (“A” grade) and 1.25% (standard grade) at room temperature.
100 µA load.
™
(Vertically Integrated PNP) pro-
@
500 mA load, and 1
@
500 mA load, and
Block Diagram
Features
n Ultra low dropout voltage
n Guaranteed 500 mA continuous output current
n Very low output noise with external capacitor
n SO-8 surface mount package
<
n
0.8 µA quiescent current when shutdown
n Low ground pin current at all loads
n 0.75% output voltage accuracy (“A” grade)
n High peak current capability (800 mA typical)
n Wide supply voltage range (16V max)
n Overtemperature/overcurrent protection
n −40˚C to +125˚C junction temperature range
Applications
n Notebook/Desktop PC
n PDA/Palmtop Computer
n Wireless Communication Terminals
n SMPS Post-Regulator
DS101339-1
VIP™is a trademark of National Semiconductor Corporation.
© 2000 National Semiconductor Corporation DS101339 www.national.com
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Connection Diagram
LP2989
SO-8 Package Type M: See NS Package Drawing Number M08A
Surface Mount Packages:
DS101339-2
Ordering Information
TABLE 1. Package Marking and Ordering Information for SO-8 (M) Devices
Output Voltage Grade Order Information Package Marking Supplied as:
2.5 A LP2989AIMX-2.5 2989AIM2.5 2500 Units on Tape and Reel
2.5 A LP2989AIM-2.5 2989AIM2.5 Shipped in Anti-Static Rails
2.5 STD LP2989IMX-2.5 2989IM2.5 2500 Units on Tape and Reel
2.5 STD LP2989IM-2.5 2989IM2.5 Shipped in Anti-Static Rails
Basic Application Circuit
DS101339-3
*
Capacitance values shown are minimum required to assure stability, but may be increased without limit. Larger output capacitor provides improved dynamic re-
sponse.
**
Shutdown must be actively terminated (see App. Hints). Tie to INPUT (Pin4) if not used.
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LP2989
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Storage Temperature Range −65˚C to +150˚C
Operating
Junction Temperature Range −40˚C to +125˚C
Lead Temperature (Soldering,
5 seconds) 260˚C
ESD Rating (Note 2) 2 kV
Input Supply Voltage (Survival) −0.3V to +16V
Input Supply Voltage
(Operating) 2.1V to +16V
Sense Pin −0.3V to +6V
Output Voltage (Survival)
(Note 4) −0.3V to +16V
I
(Survival) Short Circuit
OUT
Protected
Input-Output Voltage (Survival)
(Note 5) −0.3V to +16V
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
Symbol Parameter Conditions Typical
V
O
Output Voltage
Tolerance
Output Voltage Line
Regulation
Load Regulation 1 mA<I
(NOM) + 1V, IL= 1 mA, C
IN=VO
1mA<I
V
O
16V
1mA
V
O
16V
−25˚C ≤ T
VO(NOM) + 1V ≤ VIN≤
16V
OUT
<
500 mA
L
(NOM) + 1V ≤ VIN≤
<
<
I
500 mA
L
(NOM) + 1V ≤ VIN≤
≤ 125˚C
J
<
500 mA 0.4 %V
L
= 4.7 µF, CIN= 1 µF, V
LP2989AI-X.X
(Note 6)
Min Max Min Max
−0.75 0.75 −1.25 1.25
−1.5 1.5 −2.5 2.5
−4.0 2.5 −5.0 3.5
−3.5 2.5 −4.5 3.5
0.005
= 2V.
S/D
LP2989I-X.X
(Note 6)
0.014 0.014
0.032 0.032
%V
Units
NOM
%/V
NOM
VIN–V
O
Dropout Voltage
IL= 100 µA
(Note 7)
I
= 200 mA
L
I
= 500 mA
L
I
GND
I
(PK) Peak Output Current V
O
(MAX) Short Circuit Current RL= 0 (Steady State)
I
O
Ground Pin Current IL= 100 µA
I
= 200 mA
L
I
= 500 mA
L
<
V
0.18V 0.5 2 2
S/D
<
0.4V 0.05 0.8 0.8
V
S/D
≥ VO(NOM) − 5% 800 600 600
OUT
(Note 9)
e
n
Output Noise Voltage
(RMS)
BW = 100 Hz to
100 kHz, C
C
BYPASS
OUT
= .01 µF V
= 2.5V
Ripple Rejection f = 1 kHz, C
OUT
=10µF
OUT
=10µF
1
150
310
110
1
3
33
44
200 200
300 300
mV
425 425
650 650
175 175
200 200
µA
22
3.5 3.5
66
mA
99
µA
1000
mA
18 µV(RMS)
60 dB
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Electrical Characteristics (Continued)
LP2989
Limits in standard typeface are for TJ= 25˚C, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: VIN=VO(NOM) + 1V, IL= 1 mA, C
Symbol Parameter Conditions Typical
Output Voltage
(Note 8)
Temperature Coefficient
SHUTDOWN INPUT
V
S/D
I
S/D
S/D Input Voltage VH= O/P ON 1.4 1.6 1.6
= O/P OFF
V
L
≤ 2µA
I
IN
S/D Input Current V
= 0 0.001 −1 −1
S/D
=5V 5 15 15
V
S/D
ERROR COMPARATOR
I
OH
V
OL
V
THR
(MAX)
V
THR
(MIN)
Output “HIGH” Leakage VOH= 16V
Output “LOW” Voltage VIN=VO(NOM) − 0.5V,
(COMP) = 150 µA
I
O
Upper Threshold
Voltage
Lower Threshold
Voltage
HYST Hysteresis 2.0
Note 1: AbsoluteMaximum 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: ESD testing was performed using Human Body Model, a 100 pF capacitor discharged through a 1.5 kΩ resistor.
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 temperature is calculated using:
A
= 4.7 µF, CIN= 1 µF, V
OUT
20 ppm/˚C
0.50
0.001
150
−4.8
−6.6
= 2V.
S/D
LP2989AI-X.X
(Note 6)
LP2989I-X.X
(Note 6)
Min Max Min Max
0.18 0.18
11
22
220 220
350 350
−6.0 −3.5 −6.0 −3.5
−8.3 −2.5 −8.3 −2.5
−8.9 −4.9 −8.9 −4.9
−13.0 −3.0 −13.0 −3.0
(MAX), the junction-to-ambient thermal resistance, θ
J
Units
µA
µA
mV
%V
V
OUT
J−A
,
The value of θ
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 LP2989 output must be diode-clamped to ground.
Note 5: Theoutput PNP structure contains a diode between the V
on this diode and may induce a latch-up mode which can damage the part (see Application Hints).
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: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential.
Note 8: Temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range.
Note 9: See Typical Performance Characteristics curves.
for the SO-8 (M) package is 160˚C. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator
J−A
IN
and V
terminals that is normally reverse-biased. Forcing the output above the input will turn
OUT
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LP2989
Typical Performance Characteristics Unless otherwise specified: T
C
= 1 µF, S/D is tied to VIN,VIN=VO(NOM) + 1V, IL= 1 mA, V
IN
Input Current vs V
I
vs Shutdown
GND
IN
DS101339-5
= 2.5V.
OUT
Input Current vs V
I
vs Shutdown
GND
IN
= 25˚C, C
A
OUT
DS101339-6
= 4.7 µF,
I
vs Shutdown
GND
DS101339-7
DS101339-9
I
vs Shutdown
GND
DS101339-8
DS101339-10
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Typical Performance Characteristics Unless otherwise specified: T
C
IN
LP2989
= 1 µF, S/D is tied to VIN,VIN=VO(NOM) + 1V, IL= 1 mA, V
= 2.5V. (Continued)
OUT
= 25˚C, C
A
OUT
= 4.7 µF,
Line Transient Response
Line Transient Response
DS101339-11
Line Transient Response
DS101339-26
Line Transient Response
Load Transient Response
DS101339-15
DS101339-17
DS101339-16
Load Transient Response
DS101339-18
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LP2989
Typical Performance Characteristics Unless otherwise specified: T
C
= 1 µF, S/D is tied to VIN,VIN=VO(NOM) + 1V, IL= 1 mA, V
IN
Dropout Voltage vs Load Current
DS101339-19
Dropout Characteristics
Dropout Voltage vs Temperature
Ground Pin Current vs Load Current
= 2.5V. (Continued)
OUT
= 25˚C, C
A
OUT
DS101339-20
= 4.7 µF,
GND Pin Current vs
Temperature and Load
DS101339-21
DS101339-23
V
OUT
DS101339-22
vs Shutdown
DS101339-24
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Typical Performance Characteristics Unless otherwise specified: T
C
IN
LP2989
= 1 µF, S/D is tied to VIN,VIN=VO(NOM) + 1V, IL= 1 mA, V
= 2.5V. (Continued)
OUT
= 25˚C, C
A
OUT
= 4.7 µF,
Input Current vs V
Turn-ON Waveform
IN
DS101339-25
Turn-ON Waveform
DS101339-28
Turn-ON Waveform
Turn-ON Waveform
DS101339-29
DS101339-31
DS101339-30
Short Circuit Current vs Temperature
DS101339-32
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LP2989
Typical Performance Characteristics Unless otherwise specified: T
C
= 1 µF, S/D is tied to VIN,VIN=VO(NOM) + 1V, IL= 1 mA, V
IN
Short Circuit Current vs V
OUT
DS101339-33
Short Circuit Current
Short Circuit Current
Output Noise Density
= 2.5V. (Continued)
OUT
= 25˚C, C
A
= 4.7 µF,
OUT
DS101339-34
Output Noise Density
DS101339-35
DS101339-36
DS101339-37
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Application Hints
LP2989
EXTERNAL CAPACITORS
Like any low-dropout regulator,the LP2989 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 LP2989 input and ground
(the amount of capacitance may be increased without limit).
This capacitor must be located a distance of not more than
0.5″ 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
low-impedance 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 LP2989 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. It may 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).
DS101339-38
Stable Region For output Capacitor ESR
Important: The output capacitor must maintain its ESR
within the stable region
range of the application
The LP2989 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
over the full operating temperature
to assure stability.
operating temperature range. Some ceramic capacitors can
exhibit large changes in capacitance with temperature, so
X7R or X5R dielectric are strongly recommended.
The output capacitor must be located not more than 0.5″
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. However, 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
CERAMIC: The LP2989 was designed to work with ceramic
capacitors on the output to take advantage of the benefits
they offer: for capacitance values in the 4.7 µF range, ceramics are the least expensive and also have the lowest ESR
values (which makes them best for eliminating
high-frequency noise). The ESR of a typical 4.7 µF ceramic
capacitor is in the range of 10 mΩ to 15 mΩ, which easily
meets the ESR limits required for stability by the LP2989.
One disadvantage of ceramic capacitors is that their capacitance can vary with temperature. Many 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 2.4 µF
at high ambient temperatures (which could cause the
LP2989 to oscillate). If Z5U or Y5V capacitors are used on
the output, a
minimum capacitance value of 10 µF must be
observed.
Abetter choice for temperature coefficient in ceramic capacitors is X7R or X5R, which holds the capacitance within about
±
15% over the operating temperature range.
TANTALUM: Tantalum output capacitors are not recommended for use with the LP2989 because:
Tantalum capacitors are less desirable than ceramics for use
as output capacitors because they are typically 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.
It should also be noted that the ESR of a typical Tantalumwill
increase about 2:1 as the temperature goes from 25˚C down
to −40˚C, so some guard band must be allowed.
FILM: Polycarbonate and polypropelene film capacitors
have excellent electrical performance: their ESR is the low-
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Application Hints (Continued)
est of the three types listed, their capacitance is very stable
with temperature, and DC leakage currrent is extremely low.
One disadvantage is that film capacitors are larger in physical size than ceramic or tantalum which makes film a poor
choice for either input or output capacitors.
However, their low leakage makes them a good choice for
the noise bypass capacitor.Since the required amount of capacitance is only .01 µF,small surface-mount film capacitors
are avalable in this size.
SHUTDOWN INPUT OPERATION
The LP2989 is shut off by driving the Shutdown input low,
and turned on by pulling it high. If this feature is not to be
used, the Shutdown input should be tied to V
regulator output on at all times.
To assure proper operation, the signal source used to drive
the Shutdown 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
To prevent mis-operation, the turn-on (and turn-off) voltage
signals applied to the Shutdown input must have a slew rate
which is ≥ 40 mV/µs.
ON/OFF
to keep the
IN
.
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
ON/OFF
(see
Electrical Characteristics).
REVERSE INPUT-OUTPUT VOLTAGE
The PNP power transistor used as the pass element in the
LP2989 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 reverse-biased.
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
IN
can damage the part.
In any application where the output may be pulled above the
input, an external Schottky diode must be connected from
V
to V
IN
(cathode on VIN, anode on V
OUT
), to limit the re-
OUT
verse voltage across the LP2989 to 0.3V (see Absolute
Maximum Ratings).
LP2989
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Physical Dimensions inches (millimeters) unless otherwise noted
For Use with Ceramic Output Capacitors
LP2989 Micropower/Low Noise, 500 mA Ultra Low-Dropout Regulator
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS 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.
National Semiconductor
Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: support@nsc.com
www.national.com
SO-8 Package Type M
NS Package Number M08A
National Semiconductor
Europe
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
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.
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
Email: ap.support@nsc.com
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
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.
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