NSC LP2989AIM-1.8 Micropower 500 ma low noise low dropout regulator for applications with output voltages < 2v designed for use with very low esr output capacitor Datasheet

LP2989LV
Micropower 500 mA Low Noise Low Dropout Regulator
for Applications with Output Voltages < 2V
Designed for Use with Very Low ESR Output Capacitors
General Description
Features
The LP2989LV is a 500 mA fixed-output voltage regulator
designed to provide high performance and low noise in
applications requiring output voltages < 2V.
Output noise can be reduced to 18µV (typical) by connecting
an external 10 nF capacitor to the bypass pin.
Using an optimized VIP™ (Vertically Integrated PNP) process, the LP2989LV delivers superior performance:
Ground Pin Current: Typically 3 mA @ 500 mA load, and
110 µA @ 100 µA load.
Sleep Mode: The LP2989LV 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.
For output voltages ≥ 2V, see LP2989 datasheet.
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Ultra low dropout voltage
Guaranteed 500 mA continuous output current
Very low output noise with external capacitor
SO-8, Mini SO-8, 8 Lead LLP surface mount packages
< 0.8 µA quiescent current when shutdown
Low ground pin current at all loads
0.75% output voltage accuracy (“A” grade)
High peak current capability (800 mA typical)
Wide supply voltage range (16V max)
Overtemperature/overcurrent protection
−40˚C to +125˚C junction temperature range
Applications
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Notebook/Desktop PC
PDA/Palmtop Computer
Wireless Communication Terminals
SMPS Post-Regulator
Block Diagram
10135701
VIP™ is a trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation
DS101357
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LP2989LV Micropower 500 mA Low Noise Low Dropout Regulator for Output Voltages < 2V
Designed for Use with Very Low ESR Output Capacitors
February 2005
LP2989LV
Connection Diagrams
Surface Mount Packages:
8 Lead LLP Surface Mount Package
10135702
SO-8/Mini SO-8 Package
See NS Package Drawing Numbers M08A/MUA08A
10135750
Top View
See NS Package Number LDC08A
Ordering Information
TABLE 1. Package Marking and Ordering Information
Output Voltage
Grade
Order Information
Package Marking
Supplied as:
1.8
A
LP2989AILD-1.8
L01EA
1000 Units on Tape and
Reel
1.8
A
LP2989AILDX-1.8
L01EA
4500 Units on Tape and
Reel
1.8
STD
LP2989ILD-1.8
L01EAB
1000 Units on Tape and
Reel
1.8
STD
LP2989ILDX-1.8
L01EAB
4500 Units on Tape and
Reel
1.8
A
LP2989AIMX-1.8
2989AIM1.8
2500 Units on Tape and
Reel
1.8
A
LP2989AIM-1.8
2989AIM1.8
Shipped in Anti-Static
Rails
1.8
STD
LP2989IMX-1.8
2989IM1.8
2500 Units on Tape and
Reel
1.8
STD
LP298IM-1.8
2989IM1.8
Shipped in Anti-Static
Rails
1.8
A
LP2989AIMMX-1.8
LA5A
3500 Units on Tape and
Reel
1.8
A
LP2989AIMM-1.8
LA5A
1000 Units on Tape and
Reel
1.8
STD
LP2989IMMX-1.8
LA5B
3500 Units on Tape and
Reel
1.8
STD
LP2989IMM-1.8
LA5B
1000 Units on Tape and
Reel
8 Lead LLP
SO-8 (M)
8 Lead MSOP (MM)
For output voltages ≥ 2V, see LP2989 datasheet.
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LP2989LV
Basic Application Circuit
10135703
*Capacitance values shown are minimum required to assure stability, but may be increased without limit. Larger output capacitor provides improved dynamic
response.
**Shutdown must be actively terminated (see App. Hints). Tie to INPUT (Pin4) if not used.
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LP2989LV
Absolute Maximum Ratings (Note 1)
Input Supply Voltage
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Supply Voltage
(Operating)
2.1V to +16V
Sense Pin
−0.3V to +6V
Storage Temperature Range
−65˚C to +150˚C
Operating Junction
Range
Temperature
Output Voltage
(Note 4)
−40˚C to +125˚C
IOUT (Survival)
Lead Temperature
seconds)
(Soldering, 5
260˚C
ESD Rating (Note 2)
Power Dissipation (Note 3)
−0.3V to +16V
(Survival)
Input-Output Voltage
(Note 5)
2 kV
(Survival)
−0.3V to +16V
Short Circuit
Protected
(Survival)
−0.3V to +16V
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: VIN = VO(NOM) + 1V, IL = 1 mA, COUT = 10 µF, CIN = 2.2 µF, VS/D = 2V.
Symbol
VO
VIN (min)
IGND
Parameter
Output Voltage
Tolerance
Conditions
Typical
LP2989I-X.X
(Note 6)
Min
Max
Min
Max
−0.75
0.75
−1.25
1.25
1 mA < IL < 500 mA
VO(NOM) + 1V ≤ VIN ≤ 16V
−1.5
1.5
−2.5
2.5
−4.0
2.5
−5.0
3.5
1 mA < IL < 500 mA
VO(NOM) + 1V ≤ VIN ≤ 16V
−25˚C ≤ TJ ≤ 125˚C
−3.5
2.5
−4.5
3.5
Output Voltage Line
Regulation
VO(NOM) + 1V ≤ VIN ≤ 16V
Load Regulation
1 mA < IL < 500 mA
0.4
1.96
Minimum Input Voltage
Required To Maintain
Output Regulation
VOUT = 1.8
IL ≤ 50 mA
VOUT = 1.8
IL = 250 mA
1.98
VOUT = 1.8
IL = 500 mA
2.11
Ground Pin Current
IL = 100 µA
0.005
0.014
0.032
0.032
3
175
175
200
200
2
2
3.5
3.5
6
6
9
9
VS/D < 0.18V
0.5
2
2
VS/D < 0.4V
0.05
0.8
0.8
IO(PK)
Peak Output Current
VOUT ≥ VO(NOM) − 5%
800
IO(MAX)
Short Circuit Current
RL = 0 (Steady State) (Note
8)
1000
en
Output Noise Voltage
(RMS)
BW = 100 Hz to 100 kHz,
CBYPASS = .01 µF
Ripple Rejection
f = 1 kHz
Output Voltage
(Note 7)
Temperature Coefficient
4
%VNOM
%/V
V
1
IL = 500 mA
0.014
Units
%VNOM
110
IL = 200 mA
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LP2989AI-X.X
(Note 6)
600
µA
mA
µA
600
mA
18
µV(RMS)
60
dB
20
ppm/˚C
(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: VIN = VO(NOM) + 1V, IL = 1 mA, COUT = 10 µF, CIN = 2.2 µF, VS/D = 2V.
Symbol
Parameter
Conditions
Typical
LP2989AI-X.X
(Note 6)
Min
Max
LP2989I-X.X
(Note 6)
Min
Units
Max
SHUTDOWN INPUT
VS/D
IS/D
S/D Input Voltage
S/D Input Current
VH = O/P ON
1.4
1.6
0.18
0.001
−1
−1
5
15
15
1
1
2
2
220
220
350
350
0.50
VS/D = 0
VS/D = 5V
1.6
0.18
VL = O/P OFF
IIN ≤ 2 µA
V
µA
ERROR COMPARATOR
IOH
VOL
Output “HIGH” Leakage
Output “LOW” Voltage
VOH = 16V
0.001
VOUT = VO(NOM) − 0.5V
IO(COMP) = 150 µA
150
VTHR
(MAX)
Upper Threshold
Voltage
−4.8
VTHR
(MIN)
Lower Threshold
Voltage
−6.6
HYST
Hysteresis
2.0
−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
µA
mV
%VOUT
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: 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, TJ(MAX), the junction-to-ambient thermal resistance, θJ−A,
and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using:
The value of θJ−A for the SO-8 (M) package is 160˚C/W and the mini SO-8 (MM) package is 200˚C/W. The value θJ−A for the LLP (LD) package is specifically
dependent on PCB trace area, trace material, and the number of layers and thermal vias. For improved thermal resistance and power dissipation for the LLP
package, refer to Application Note AN-1187.Exceeding the maximum allowable power 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 LP2989LV output must be diode-clamped to ground.
Note 5: The output PNP structure contains a diode between the VIN and VOUT terminals that is normally reverse-biased. Forcing the output above the input will turn
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: Temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range.
Note 8: See Typical Performance Characteristics curves.
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LP2989LV
Electrical Characteristics
LP2989LV
Typical Performance Characteristics Unless otherwise specified: TA = 25˚C, COUT = 10 µF,
CIN = 2.2 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 1.8V.
IGND vs Shutdown
IGND vs Shutdown
10135707
10135708
IGND vs Shutdown
IGND vs Shutdown
10135709
10135710
GND Pin Current vs
Temperature and Load
Ground Pin Current vs Load Current
10135722
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10135723
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Short Circuit Current vs Temperature
Short Circuit Current
10135734
10135732
Short Circuit Current
Minimum VIN vs Load Current
10135735
10135739
Typical Temperature vs VOUT (LP2989-1.8)
10135755
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LP2989LV
Typical Performance Characteristics Unless otherwise specified: TA = 25˚C, COUT = 10 µF,
CIN = 2.2 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 1.8V. (Continued)
LP2989LV
Application Hints
LLP Package Devices
The LP2989LV is offered in the 8 lead LLP surface mount
package to allow for increased power dissipation compared
to the SO-8 and Mini SO-8. For details on thermal performance as well as mounting and soldering specifications,
refer to Application Note AN-1187.
For output voltages ≥ 2V, see LP2989 datasheet.
EXTERNAL CAPACITORS
Like any low-dropout regulator, the LP2989LV requires external capacitors for regulator stability.These capacitors
must be correctly selected for good performance.
INPUT CAPACITOR: An input capacitor whose capacitance
is at least 2.2 µF is required between the LP2989LV input
and ground (the amount of capacitance may be increased
without limit).
Characterization testing performed on the LP2989LV has
shown that if the amount of actual input capacitance drops
below about 1.5 µF, an unstable operating condition may
result. Therefore, the next larger standard size (2.2 µF) is
specified as the minimum required input capacitance. Capacitor tolerance and temperature variation must be considered when selecting a capacitor (see Capacitor Characteristics section) to assure the minimum requirement of 1.5 µF
is met over all operating conditions.
The input capacitor must be located at a distance of not
more than 0.5" from the input pin and returned to a clean
analog ground. Any good quality ceramic or tantalum may be
used for this capacitor, assuming the minimum capacitance
requirement is met.
OUTPUT CAPACITOR: The LP2989LV requires a ceramic
output capacitor whose size is at least 10 µF. The actual
amount of capacitance on the output must never drop below
about 7 µF or unstable operation may result. For this reason,
capacitance tolerance and temperature characteristics must
be considered when selecting an output capacitor
10135738
Stable Region For Output Capacitor ESR
Important: The output capacitor must maintain its ESR
within the stable region over the full operating temperature
range of the application to assure stability.
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. (See Capacitor Characteristics section).
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 LP2989LV 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 4 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).
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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 LP2989LV was designed to work with ceramic capacitors on the output to take advantage of the
benefits they offer: for capacitance values in the 10 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 10 µF ceramic
capacitor is in the range of 5 mΩ to 10 mΩ, which meets the
ESR limits required for stability by the LP2989LV.
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.
8
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.
(Continued)
This could cause problems if a 10 µF Y5V capacitor were
used on the output since it will drop down to approximately
5 µF at high ambient temperatures (which could cause the
LP2989LV to oscillate).
Another significant problem with Z5U and Y5V dielectric
devices is that the capacitance drops severely with applied
voltage. A typical Z5U or Y5V capacitor can lose 60% of its
rated capacitance with half of the rated voltage applied to it.
SHUTDOWN INPUT OPERATION
The LP2989LV 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 VIN to keep the
regulator output on at all times.
For these reasons, X7R and X5R type ceramic capacitors must be used on the input and output of the
LP2989LV.
TANTALUM: Tantalum output capacitors are not recommended for use with the LP2989LV 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 10 µF range.
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 VON/OFF.
REVERSE INPUT-OUTPUT VOLTAGE
The PNP power transistor used as the pass element in the
LP2989LV has an inherent diode connected between the
regulator output and input.
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.
Most 10 µF Tantalum capacitors have ESR values higher
than the 0.5Ω maximum limit required to make the
LP2989LV stable.
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.
FILM: Polycarbonate and polypropelene film capacitors
have excellent electrical performance: their ESR is the lowest of the three types listed, their capacitance is very stable
with temperature, and DC leakage currrent is extremely low.
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 VIN (and out the ground pin), which
can damage the part.
In any application where the output may be pulled above the
input, an external Schottky diode must be connected from
VIN to VOUT (cathode on VIN, anode on VOUT), to limit the
reverse voltage across the LP2989LV to 0.3V (see Absolute
Maximum Ratings).
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LP2989LV
Application Hints
LP2989LV
Physical Dimensions
inches (millimeters)
unless otherwise noted
SO-8 Package Type M
NS Package Number M08A
mini SO-8 Package Type MM
NS Package Number MUA08A
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10
inches (millimeters) unless otherwise noted (Continued)
8 Lead LLP Surface Mount PackagePackage
NS Package Number LDC08A
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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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LP2989LV Micropower 500 mA Low Noise Low Dropout Regulator for Output Voltages < 2V
Designed for Use with Very Low ESR Output Capacitors
Physical Dimensions
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