LP298IM-1.8 [NSC]
Micropower 500 mA Low Noise Low Dropout Regulator for Applications with Output Voltages < 2V Designed for Use with Very Low ESR Output Capacitors; 微500毫安低噪声低压差稳压器的应用程序与输出电压\u003c 2V具有极低的ESR输出电容器设计用于
| 型号： | LP298IM-1.8 |
| 厂家： | 
National Semiconductor |
| 描述： | Micropower 500 mA Low Noise Low Dropout Regulator for Applications with Output Voltages < 2V Designed for Use with Very Low ESR Output Capacitors |
| 文件： | 总11页 (文件大小：685K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
February 2005
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
n Ultra low dropout voltage
The LP2989LV is a 500 mA fixed-output voltage regulator
designed to provide high performance and low noise in
n Guaranteed 500 mA continuous output current
n Very low output noise with external capacitor
n SO-8, Mini SO-8, 8 Lead LLP surface mount packages
<
applications requiring output voltages 2V.
Output noise can be reduced to 18µV (typical) by connecting
an external 10 nF capacitor to the bypass pin.
<
n
0.8 µA quiescent current when shutdown
™
Using an optimized VIP (Vertically Integrated PNP) pro-
n Low ground pin current at all loads
cess, the LP2989LV delivers superior performance:
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
@
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 quies-
cent current when shutdown pin is pulled low.
Error Flag: The built-in error flag goes low when the output
drops approximately 5% below nominal.
Applications
Precision Output: Guaranteed output voltage accuracy is
0.75% (“A” grade) and 1.25% (standard grade) at room
temperature.
n Notebook/Desktop PC
n PDA/Palmtop Computer
n Wireless Communication Terminals
n SMPS Post-Regulator
For output voltages ≥ 2V, see LP2989 datasheet.
Block Diagram
10135701
™
VIP is a trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation
DS101357
www.national.com
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
8 Lead LLP
Grade
A
Order Information
LP2989AILD-1.8
LP2989AILDX-1.8
LP2989ILD-1.8
Package Marking
Supplied as:
1.8
1.8
1.8
1.8
L01EA
1000 Units on Tape and
Reel
A
L01EA
4500 Units on Tape and
Reel
STD
STD
L01EAB
1000 Units on Tape and
Reel
LP2989ILDX-1.8
L01EAB
4500 Units on Tape and
Reel
SO-8 (M)
1.8
1.8
1.8
1.8
A
LP2989AIMX-1.8
LP2989AIM-1.8
LP2989IMX-1.8
LP298IM-1.8
2989AIM1.8
2989AIM1.8
2989IM1.8
2989IM1.8
2500 Units on Tape and
Reel
A
Shipped in Anti-Static
Rails
STD
STD
2500 Units on Tape and
Reel
Shipped in Anti-Static
Rails
8 Lead MSOP (MM)
1.8
A
LP2989AIMMX-1.8
LP2989AIMM-1.8
LP2989IMMX-1.8
LP2989IMM-1.8
LA5A
LA5A
LA5B
LA5B
3500 Units on Tape and
Reel
1.8
1.8
1.8
A
1000 Units on Tape and
Reel
STD
STD
3500 Units on Tape and
Reel
1000 Units on Tape and
Reel
For output voltages ≥ 2V, see LP2989 datasheet.
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2
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.
3
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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 (Survival)
Input Supply Voltage
(Operating)
−0.3V to +16V
2.1V to +16V
−0.3V to +6V
Sense Pin
Storage Temperature Range
Operating Junction Temperature
Range
−65˚C to +150˚C
Output Voltage (Survival)
(Note 4)
−0.3V to +16V
Short Circuit
Protected
−40˚C to +125˚C
IOUT (Survival)
Lead Temperature (Soldering, 5
seconds)
260˚C
2 kV
Input-Output Voltage (Survival)
(Note 5)
ESD Rating (Note 2)
Power Dissipation (Note 3)
−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. Un-
less otherwise specified: VIN = VO(NOM) + 1V, IL = 1 mA, COUT = 10 µF, CIN = 2.2 µF, VS/D = 2V.
LP2989AI-X.X
LP2989I-X.X
(Note 6)
(Note 6)
Symbol
VO
Parameter
Conditions
Typical
Units
Min
−0.75
−1.5
−4.0
−3.5
Max
0.75
1.5
Min
−1.25
−2.5
−5.0
−4.5
Max
1.25
2.5
Output Voltage
Tolerance
<
<
1 mA IL 500 mA
VO(NOM) + 1V ≤ VIN ≤ 16V
2.5
3.5
%VNOM
<
<
1 mA IL 500 mA
2.5
3.5
VO(NOM) + 1V ≤ VIN ≤ 16V
−25˚C ≤ TJ ≤ 125˚C
Output Voltage Line
Regulation
VO(NOM) + 1V ≤ VIN ≤ 16V
0.014
0.014
0.005
0.4
%/V
0.032
0.032
<
<
Load Regulation
1 mA IL 500 mA
%VNOM
VOUT = 1.8
IL ≤ 50 mA
VOUT = 1.8
IL = 250 mA
VOUT = 1.8
IL = 500 mA
IL = 100 µA
1.96
1.98
2.11
Minimum Input Voltage
Required To Maintain
Output Regulation
VIN (min)
V
IGND
Ground Pin Current
175
200
2
175
200
2
110
1
µA
IL = 200 mA
IL = 500 mA
3.5
6
3.5
6
mA
3
9
9
<
VS/D 0.18V
0.5
0.05
800
2
2
µA
<
VS/D 0.4V
0.8
0.8
IO(PK)
Peak Output Current
Short Circuit Current
VOUT ≥ VO(NOM) − 5%
RL = 0 (Steady State) (Note
8)
600
600
mA
IO(MAX)
1000
18
en
Output Noise Voltage
(RMS)
BW = 100 Hz to 100 kHz,
CBYPASS = .01 µF
f = 1 kHz
µV(RMS)
dB
Ripple Rejection
60
Output Voltage
(Note 7)
20
ppm/˚C
Temperature Coefficient
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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. Un-
less otherwise specified: VIN = VO(NOM) + 1V, IL = 1 mA, COUT = 10 µF, CIN = 2.2 µF, VS/D = 2V.
LP2989AI-X.X
LP2989I-X.X
(Note 6)
(Note 6)
Symbol
Parameter
Conditions
Typical
Units
Min
1.6
Max
Min
1.6
Max
SHUTDOWN INPUT
VS/D S/D Input Voltage
VH = O/P ON
1.4
V
VL = O/P OFF
IIN ≤ 2 µA
VS/D = 0
0.18
0.18
0.50
IS/D
S/D Input Current
0.001
5
−1
15
−1
15
µA
VS/D = 5V
ERROR COMPARATOR
IOH
Output “HIGH” Leakage VOH = 16V
1
1
0.001
150
µA
2
2
VOL
Output “LOW” Voltage
VOUT = VO(NOM) − 0.5V
IO(COMP) = 150 µA
220
350
−3.5
−2.5
−4.9
−3.0
220
350
−3.5
−2.5
−4.9
−3.0
mV
VTHR
Upper Threshold
Voltage
−6.0
−8.3
−6.0
−8.3
−4.8
(MAX)
VTHR
(MIN)
Lower Threshold
Voltage
−8.9
−8.9
%VOUT
−6.6
2.0
−13.0
−13.0
HYST
Hysteresis
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, T (MAX), the junction-to-ambient thermal resistance, θ
,
J−A
J
and the ambient temperature, T . The maximum allowable power dissipation at any ambient temperature is calculated using:
A
The value of θ
for the SO-8 (M) package is 160˚C/W and the mini SO-8 (MM) package is 200˚C/W. The value θ
for the LLP (LD) package is specifically
J−A
J−A
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 V and V
terminals that is normally reverse-biased. Forcing the output above the input will turn
OUT
IN
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.
5
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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
Ground Pin Current vs Load Current
Temperature and Load
10135722
10135723
www.national.com
6
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)
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
7
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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 perfor-
mance 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 ex-
ternal 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).
10135738
Stable Region For Output Capacitor ESR
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. Ca-
pacitor tolerance and temperature variation must be consid-
ered when selecting a capacitor (see Capacitor Character-
istics section) to assure the minimum requirement of 1.5 µF
is met over all operating conditions.
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 Character-
istics section).
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.
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 capaci-
tor to the Bypass pin significantly reduces noise on the
regulator output. However, the capacitor is connected di-
rectly to a high-impedance circuit in the bandgap reference.
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
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 ex-
ceed 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 regula-
tor 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 types of capacitors best suited for the noise bypass
capacitor are ceramic and film. High-quality ceramic capaci-
tors 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.
The output capacitor must meet the requirement for mini-
mum amount of capacitance and also have an ESR (equiva-
lent 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).
CAPACITOR CHARACTERISTICS
CERAMIC: The LP2989LV was designed to work with ce-
ramic 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 capaci-
tance 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.
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8
One disadvantage is that film capacitors are larger in physi-
cal size than ceramic or tantalum which makes film a poor
choice for either input or output capacitors.
Application Hints (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).
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 capaci-
tors are avalable in this size.
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 capaci-
tors must be used on the input and output of the
LP2989LV.
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
TANTALUM: Tantalum output capacitors are not recom-
mended for use with the LP2989LV because:
Tantalum capacitors are less desirable than ceramics for use
as output capacitors because they are typically more expen-
sive when comparing equivalent capacitance and voltage
ratings in the 1 µF to 10 µF range.
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.
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.
Most 10 µF Tantalum capacitors have ESR values higher
than the 0.5Ω maximum limit required to make the
LP2989LV stable.
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.
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.
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).
FILM: Polycarbonate and polypropelene film capacitors
have excellent electrical performance: their ESR is the low-
est of the three types listed, their capacitance is very stable
with temperature, and DC leakage currrent is extremely low.
9
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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
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8 Lead LLP Surface Mount PackagePackage
NS Package Number LDC08A
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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(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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