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PDF LP2986AIMMX-3.3 Data sheet ( Hoja de datos )
| Número de pieza | LP2986AIMMX-3.3 | |
| Descripción | Micropower/ 200 mA Ultra Low-Dropout Fixed or Adjustable Voltage Regulator | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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March 1999
LP2986
Micropower, 200 mA Ultra Low-Dropout Fixed or
Adjustable Voltage Regulator
General Description
The LP2986 is a 200 mA precision LDO voltage regulator
which offers the designer a higher performance version of
the industry standard LP2951.
Using an optimized VIP™ (Vertically Integrated PNP) pro-
cess, the LP2986 delivers superior performance:
Dropout Voltage: Typically 180 mV @ 200 mA load, and 1
mV @ 1 mA load.
Ground Pin Current: Typically 1 mA @ 200 mA load, and
200 µA @ 10 mA load.
Sleep Mode: The LP2986 draws less than 1 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: The standard product versions available
can be pin-strapped (using the internal resistive divider) to
provide output voltages of 5.0V, 3.3V, or 3.0V with guaran-
teed accuracy of 0.5% (“A” grade) and 1% (standard grade)
at room temperature.
Features
n Ultra low dropout voltage
n Guaranteed 200 mA output current
n SO-8 and mini-SO8 surface mount packages
n <1 µA quiescent current when shutdown
n Low ground pin current at all loads
n 0.5% output voltage accuracy (“A” grade)
n High peak current capability (400 mA typical)
n Wide supply voltage range (16V max)
n Overtemperature/overcurrent protection
n −40˚C to +125˚C junction temperature range
Applications
n Cellular Phone
n Palmtop/Laptop Computer
n Camcorder, Personal Stereo, Camera
Block Diagram
VIP™ is a trademark of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation DS012935
DS012935-1
www.national.com
1 page  
Electrical Characteristics (Continued)
Limits in standard typeface are for T J = 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 = 4.7 µF, CIN = 2.2 µF, VS/D = 2V.
Symbol
Parameter
Conditions
Typical
LM2986AI-X.X
(Note 6)
Min Max
LM2986I-X.X
(Note 6)
Min Max
Units
Output Voltage
(Note 9)
Temperature Coefficient
20
ppm/˚C
FEEDBACK PIN
VFB Feedback Pin Voltage
FB Pin Voltage
Temperature Coefficient
(Note 10)
(Note 9)
1.21
1.25
1.20
1.26
1.23
1.20
1.26
1.19
1.27
1.23 1.19 1.28 1.18 1.29
V
20 ppm/˚C
IFB
Feedback Pin Bias
IL = 200 mA
Current
150
330
760
330
nA
760
FB Pin Bias Current
(Note 9)
Temperature Coefficient
0.1
nA/˚C
SHUTDOWN INPUT
VS/D
S/D Input Voltage
(Note 8)
IS/D S/D Input Current
ERROR COMPARATOR
IOH Output “HIGH” Leakage
VH = O/P ON
VL = O/P OFF
VS/D = 0
VS/D = 5V
VOH = 16V
VOL
VTHR
(MAX)
VTHR
(MIN)
HYST
Output “LOW” Voltage
Upper Threshold
Voltage
Lower Threshold
Voltage
Hysteresis
VIN = VO(NOM) − 0.5V,
IO(COMP) = 300 µA
1.4
0.55
0
5
0.01
150
−4.6
−6.6
2.0
1.6
−5.5
−7.7
−8.9
−13.0
0.18
−1
15
1
2
220
350
−3.5
−2.5
−4.9
−3.3
1.6
−5.5
−7.7
−8.9
−13.0
0.18
−1
15
1
2
220
350
−3.5
−2.5
−4.9
−3.3
V
µA
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 de-
vice outside of its rated operating conditions.
Note 2: The ESD rating of the Feedback pin is 500V and the Tap pin is 1.5 kV.
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. 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 LM2986 output must be diode-clamped to ground.
Note 5: The output PNP structure contains a diode between the V IN 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: 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: To prevent mis-operation, the Shutdown input must be driven by a signal that swings above VH and below VL with a slew rate not less than 40 mV/µs (see
Application Hints).
Note 9: Temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range.
Note 10: VFB ≤ VOUT ≤ (VIN − 1), 2.5V ≤ VIN ≤ 16V, 100 µA ≤ IL ≤ 200 mA, TJ ≤ 125˚C.
Note 11: See Typical Performance Characteristics curves.
5 www.national.com
5 Page 
Application Hints
EXTERNAL CAPACITORS
Like any low-dropout regulator, external capacitors are re-
quired to assure stability. These capacitors must be correctly
selected for proper performance.
INPUT CAPACITOR: An input capacitor (≥ 2.2 µF) is re-
quired between the LP2986 input and ground (amount of ca-
pacitance 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 or tantalum may be used
for this capacitor.
OUTPUT CAPACITOR: The output capacitor must meet the
requirement for minimum amount of capacitance and also
have an appropriate E.S.R. (equivalent series resistance)
value.
Curves are provided which show the allowable ESR range
as a function of load current for various output voltages and
capacitor values (see ESR curves below).
ESR Curves For 5V Output
ESR Curves For 2.5V Output
DS012935-6
DS012935-7
IMPORTANT: The output capacitor must maintain its ESR in
the stable region over the full operating temperature range of
the application to assure stability.
The minimum required amount of output capacitance is
4.7 µF. 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 re-
quired amount of output capacitance is provided over the full
operating temperature range. A good Tantalum capacitor will
show very little variation with temperature, but a ceramic
may not be as good (see next section).
CAPACITOR CHARACTERISTICS
TANTALUM: The best choice for size, cost, and perfor-
mance are solid tantalum capacitors. Available from many
sources, their typical ESR is very close to the ideal value re-
quired on the output of many LDO regulators.
Tantalums also have good temperature stability: a 4.7 µF
was tested and showed only a 10% decline in capacitance
as the temperature was decreased from +125˚C to −40˚C.
The ESR increased only about 2:1 over the same range of
temperature.
However, it should be noted that the increasing ESR at lower
temperatures present in all tantalums can cause oscillations
when marginal quality capacitors are used (where the ESR
of the capacitor is near the upper limit of the stability range at
room temperature).
CERAMIC: For a given amount of a capacitance, ceramics
are usually larger and more costly than tantalums.
Be warned that the ESR of a ceramic capacitor can be low
enough to cause instability: a 2.2 µF ceramic was measured
and found to have an ESR of about 15 mΩ.
If a ceramic capacitor is to be used on the LP2986 output, a
1Ω resistor should be placed in series with the capacitor to
provide a minimum ESR for the regulator.
Another disadvantage of ceramic capacitors is that their ca-
pacitance varies a lot with temperature:
Large ceramic capacitors are typically manufactured with the
Z5U temperature characteristic, which results in the capaci-
tance dropping by a 50% as the temperature goes from 25˚C
to 80˚C.
This means you have to buy a capacitor with twice the mini-
mum COUT to assure stable operation up to 80˚C.
ALUMINUM: The large physical size of aluminum electrolyt-
ics makes them unattractive for use with the LP2986. Their
ESR characteristics are also not well suited to the require-
ments of LDO regulators.
The ESR of an aluminum electrolytic is higher than a tanta-
lum, and it also varies greatly with temperature.
A typical aluminum electrolytic can exhibit an ESR increase
of 50X when going from 20˚C to −40˚C. Also, some alumi-
num electrolytics can not be used below −25˚C because the
electrolyte will freeze.
USING AN EXTERNAL RESISTIVE DIVIDER
The LP2986 output voltage can be programmed using an ex-
ternal resistive divider (see Basic Application Circuits).
The resistor connected between the Feedback pin and
ground should be 51.1k. The value for the other resistor (R1)
connected between the Feedback pin and the regulated out-
put is found using the formula:
VOUT = 1.23 x (1 + R1/51.1k)
It should be noted that the 25 µA of current flowing through
the external divider is approximately equal to the current
saved by not connecting the internal divider, which means
the quiescent current is not increased by using external re-
sistors.
11 www.national.com
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet LP2986AIMMX-3.3.PDF ] | |
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