LP2985AIBL-3.3 [ETC]
VOLT REGULATOR|FIXED|+3.3V|BIPOLAR|BGA|5PIN|PLASTIC ; VOLT稳压器|固定| + 3.3V |双极| BGA | 5PIN |塑料\n
| 型号： | LP2985AIBL-3.3 |
| 厂家： | 
ETC |
| 描述： | VOLT REGULATOR|FIXED|+3.3V|BIPOLAR|BGA|5PIN|PLASTIC
|
| 文件： | 总18页 (文件大小：472K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
May 2002
LP2985
Micropower 150 mA Low-Noise Ultra Low-Dropout
Regulator in SOT-23 and micro SMD Packages
Designed for Use with Very Low ESR Output Capacitors
General Description
The LP2985 is a 150 mA, fixed-output voltage regulator
designed to provide ultra low-dropout and low noise in bat-
tery powered applications.
Features
n Ultra low dropout voltage
n Guaranteed 150 mA output current
n Smallest possible size (SOT-23, micro SMD package)
n Requires minimum external components
n Stable with low-ESR output capacitor
™
Using an optimized VIP (Vertically Integrated PNP) pro-
cess, the LP2985 delivers unequalled performance in all
specifications critical to battery-powered designs:
<
n
1 µA quiescent current when shut down
@
Dropout Voltage: Typically 300 mV
150 mA load, and
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 ZOUT: 0.3Ω typical (10 Hz to 1 MHz)
n Overtemperature/overcurrent protection
n −40˚C to +125˚C junction temperature range
n Custom voltages available
@
7 mV 1 mA load.
@
Ground Pin Current: Typically 850 µA 150 mA load, and
@
75 µA 1 mA load.
Enhanced Stability: The LP2985 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 micro SMD packages
use absolute minimum board space.
Applications
n Cellular Phone
Precision Output: 1% tolerance output voltages available
(A grade).
n Palmtop/Laptop Computer
n Personal Digital Assistant (PDA)
n Camcorder, Personal Stereo, Camera
Low Noise: By adding a 10 nF bypass capacitor, output
noise can be reduced to 30 µV (typical).
Multiple voltage options, from 2.5V to 5.0V, are available as
standard products. Consult factory for custom voltages.
Block Diagram
10014001
™
VIP is a trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation
DS100140
www.national.com
Basic Application Circuit
10014002
*ON/OFF input must be actively terminated. Tie to V if this function is not to be used.
IN
**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).
Connection Diagrams
5-Lead Small Outline Package (M5)
micro SMD, 5 Bump Package (BPA05 & BLA05)
10014003
Top View
See NS Package Number MF05A
For ordering information see Table 1
10014046
Top View
See NS Package Number BPA05 & BLA05
Note: The actual physical placement of the package marking will vary from
part to part. Package marking contains date code and lot traceability
information, and will vary considerably. Package marking does not correlate
to device type.
Pin Descrption
Name
Pin Number
micro SMD
Function
SOT-23
VIN
1
2
3
4
5
C3
A1
A3
B2
C1
Input Voltage
GND
Common Ground (device substrate)
Logic high enable input
ON/OFF
BYPASS
VOUT
Bypass capacitor for low noise operation
Regulated output voltage
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2
Ordering Information
TABLE 1. Package Marking and Ordering Information
Output Voltage
Grade
Package
Order Information
Supplied as:
(V)
Marking
5-Lead Small Outline Package (M5)
For output voltages ≤ 2.3V, refer to LP2985LV datasheet.
2.5
2.5
2.5
2.5
2.6
2.6
2.6
2.6
2.7
2.7
2.7
2.7
2.8
2.8
2.8
2.8
2.9
2.9
2.9
2.9
3.0
3.0
3.0
3.0
3.1
3.1
3.1
3.1
3.2
3.2
3.2
3.2
3.3
3.3
3.3
3.3
3.5
3.5
3.5
3.5
3.6
3.6
3.6
3.6
3.8
A
A
LP2985AIM5X-2.5
LP2985AIM5-2.5
LP2985IM5X-2.5
LP2985IM5-2.5
LP2985AIM5X-2.6
LP2985AIM5-2.6
LP2985IM5X-2.6
LP2985IM5-2.6
LP2985AIM5X-2.7
LP2985AIM5-2.7
LP2985IM5X-2.7
LP2985IM5-2.7
LP2985AIM5X-2.8
LP2985AIM5-2.8
LP2985IM5X-2.8
LP2985IM5-2.8
LP2985AIM5X-2.9
LP2985AIM5-2.9
LP2985IM5X-2.9
LP2985IM5-2.9
LP2985AIM5X-3.0
LP2985AIM5-3.0
LP2985IM5X-3.0
LP2985IM5-3.0
LP2985AIM5X-3.1
LP2985AIM5-3.1
LP2985IM5X-3.1
LP2985IM5-3.1
LP2985AIM5X-3.2
LP2985AIM5-3.2
LP2985IM5X-3.2
LP2985IM5-3.2
LP2985AIM5X-3.3
LP2985AIM5-3.3
LP2985IM5X-3.3
LP2985IM5-3.3
LP2985AIM5X-3.5
LP2985AIM5-3.5
LP2985IM5X-3.5
LP2985IM5-3.5
LP2985AIM5X-3.6
LP2985AIM5-3.6
LP2985IM5X-3.6
LP2985IM5-3.6
LP2985AIM5X-3.8
LAUA
LAUA
LAUB
LAUB
LCEA
LCEA
LCEB
LCEB
LALA
LALA
LALB
LALB
L0KA
L0KA
L0KB
L0KB
LAXA
LAXA
LAXB
LAXB
L0OA
L0OA
L0OB
L0OB
L0PA
L0PA
L0PB
L0PB
L0QA
L0QA
L0QB
L0QB
L0RA
L0RA
L0RB
L0RB
LAIA
3000 Units on Tape and Reel
1000 Units on Tape and Reel
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3000 Units on Tape and Reel
1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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1000 Units on Tape and Reel
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STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
LAIA
STD
STD
A
LAIB
LAIB
L0SA
L0SA
L0SB
L0SB
L0YA
A
STD
STD
A
3
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Ordering Information (Continued)
TABLE 1. Package Marking and Ordering Information (Continued)
Output Voltage
(V)
Package
Marking
L0YA
L0YB
L0YB
L0TA
L0TA
L0TB
L0TB
LA7A
LA7A
LA7B
LA7B
LAJA
LAJA
LAJB
LAJB
LAKA
LAKA
LAKB
LAKB
L0UA
L0UA
L0UB
L0UB
LFYA
LFYA
LFYB
LFYB
LF6A
LF6A
LF6B
LF6B
Grade
Order Information
Supplied as:
3.8
A
STD
STD
A
LP2985AIM5-3.8
LP2985IM5X-3.8
LP2985IM5-3.8
LP2985AIM5X-4.0
LP2985AIM5-4.0
LP2985IM5X-4.0
LP2985IM5-4.0
LP2985AIM5X-4.5
LP2985AIM5-4.5
LP2985IM5X-4.5
LP2985IM5-4.5
LP2985AIM5X-4.7
LP2985AIM5-4.7
LP2985IM5X-4.7
LP2985IM5-4.7
LP2985AIM5X-4.8
LP2985AIM5-4.8
LP2985IM5X-4.8
LP2985IM5-4.8
LP2985AIM5X-5.0
LP2985AIM5-5.0
LP2985IM5X-5.0
LP2985IM5-5.0
LP2985AIM5X-5.3
LP2985AIM5-5.3
LP2985IM5X-5.3
LP2985IM5-5.3
LP2985AIM5X-6.1
LP2985AIM5-6.1
LP2985IM5X-6.1
LP2985IM5-6.1
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
3000 Units on Tape and Reel
1000 Units on Tape and Reel
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1000 Units on Tape and Reel
3.8
3.8
4.0
4.0
A
4.0
STD
STD
A
4.0
4.5
4.5
A
4.5
STD
STD
A
4.5
4.7
4.7
A
4.7
STD
STD
A
4.7
4.8
4.8
A
4.8
STD
STD
A
4.8
5.0
5.0
A
5.0
STD
STD
A
5.0
5.3
5.3
A
5.3
STD
STD
A
5.3
6.1
6.1
A
6.1
STD
STD
6.1
micro SMD, 5 Bump Package (BPA05 - 170 µm ball)
2.4
2.4
2.4
2.4
2.5
2.5
2.5
2.5
2.6
2.6
2.6
2.6
2.8
2.8
2.8
A
A
LP2985AIBP-2.4
LP2985AIBPX-2.4
LP2985IBP-2.4
LP2985IBPX-2.4
LP2985AIBP-2.5
LP2985AIBPX-2.5
LP2985IBP-2.5
LP2985IBPX-2.5
LP2985AIBP-2.6
LP2985AIBPX-2.6
LP2985IBP-2.6
LP2985IBPX-2.6
LP2985AIBP-2.8
LP2985AIBPX-2.8
LP2985IBP-2.8
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
STD
STD
A
A
STD
STD
A
A
STD
STD
A
A
STD
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4
Ordering Information (Continued)
TABLE 1. Package Marking and Ordering Information (Continued)
Output Voltage
Package
Marking
Grade
Order Information
Supplied as:
(V)
2.8
2.9
2.9
2.9
2.9
3.0
3.0
3.0
3.0
3.3
3.3
3.3
3.3
3.6
3.6
3.6
3.6
4.0
4.0
4.0
4.0
5.0
5.0
5.0
5.0
STD
A
LP2985IBPX-2.8
LP2985AIBP-2.9
LP2985AIBPX-2.9
LP2985IBP-2.9
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
A
STD
STD
A
LP2985IBPX-2.9
LP2985AIBP-3.0
LP2985AIBPX-3.0
LP2985IBP-3.0
A
STD
STD
A
LP2985IBPX-3.0
LP2985AIBP-3.3
LP2985AIBPX-3.3
LP2985IBPX-3.3
LP2985IBPX-3.3
LP2985AIBP-3.6
LP2985AIBPX-3.6
LP2985IBP-3.6
A
STD
STD
A
A
STD
STD
A
LP2985IBPX-3.6
LP2985AIBP-4.0
LP2985AIBPX-4.0
LP2985IBP-4.0
A
STD
STD
A
LP2985IBPX-4.0
LP2985AIBP-5.0
LP2985AIBPX-5.0
LP2985IBP-5.0
A
STD
STD
LP2985IBPX-5.0
micro SMD, 5 Bump Package (BLA05 - 300 µm ball)
2.85
2.85
2.85
2.85
3.0
A
A
LP2985AIBL-285
LP2985AIBLX-285
LP2985IBL-285
LP2985IBLX-285
LP2985AIBL-3.0
LP2985AIBLX-3.0
LP2985IBL-3.0
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
250 Units on Tape and Reel
3000 Units on Tape and Reel
STD
STD
A
3.0
A
3.0
STD
STD
A
3.0
LP2985IBLX-3.0
LP2985AIBL-3.3
LP2985AIBLX-3.3
LP2985IBL-3.3
3.3
3.3
A
3.3
STD
STD
3.3
LP2985IBLX-3.3
5
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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)
Shutdown Input Voltage (Survival)
Output Voltage (Survival, (Note 4))
IOUT (Survival)
−0.3V to +16V
2.5V to +16V
−0.3V to +16V
−0.3V to +9V
Short Circuit
Protected
Storage Temperature Range
Operating Junction Temperature
Range
−65˚C to +150˚C
−40˚C to +125˚C
260˚C
Input-Output Voltage (Survival,
(Note 5))
−0.3V to +16V
Lead Temp. (Soldering, 5 sec.)
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. Un-
less otherwise specified: VIN = VO(NOM) + 1V, IL = 1 mA, CIN = 1 µF, COUT = 4.7 µF, VON/OFF = 2V.
LP2985AI-X.X
LP2985I-X.X
Symbol
Parameter
Conditions
Typ
(Note 6)
(Note 6)
Units
Min
−1.0
−1.5
−2.5
−2.5
−3.5
Max
1.0
Min
−1.5
−2.5
−3.5
−3.0
−4.0
Max
1.5
∆VO
Output Voltage
Tolerance
IL = 1 mA
1 mA ≤ IL ≤ 50 mA
1.5
2.5
2.5
3.5
%VNOM
1 mA ≤ IL ≤ 150 mA
VO(NOM)+1V ≤ VIN ≤ 16V
2.5
3.0
3.5
4.0
Output Voltage
Line Regulation
0.007
0.014
0.014
%/V
0.032
0.032
VIN–VO
Dropout Voltage
(Note 7)
IL = 0
1
3
5
3
5
IL = 1 mA
IL = 10 mA
IL = 50 mA
IL = 150 mA
IL = 0
7
10
10
15
15
40
60
60
mV
90
90
120
280
65
150
225
350
575
95
150
225
350
575
95
IGND
Ground Pin Current
125
110
170
220
400
600
1000
1500
2500
0.8
2
125
110
170
220
400
600
1000
1500
2500
0.8
2
IL = 1 mA
IL = 10 mA
IL = 50 mA
IL = 150 mA
75
120
350
850
µA
<
VON/OFF 0.3V
0.01
0.05
1.4
<
VON/OFF 0.15V
ON/OFF Input Voltage High = O/P ON
(Note 8)
VON/OFF
1.6
1.6
V
Low = O/P OFF
0.55
0.01
5
0.15
−2
0.15
−2
ION/OFF
ON/OFF Input Current VON/OFF = 0
VON/OFF = 5V
µA
15
15
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6
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, CIN = 1 µF, COUT = 4.7 µF, VON/OFF = 2V.
LP2985AI-X.X
LP2985I-X.X
Symbol
Parameter
Conditions
Typ
(Note 6)
(Note 6)
Units
Min
Max
Min
Max
en
Output Noise
BW = 300 Hz to 50 kHz,
COUT = 10 µF
Voltage (RMS)
30
45
µV
dB
CBYPASS = 10 nF
Ripple Rejection
f = 1 kHz, CBYPASS = 10 nF
COUT = 10 µF
IO(SC)
IO(PK)
Short Circuit Current
Peak Output Current
RL = 0 (Steady State)
(Note 9)
400
350
mA
mA
VOUT ≥ Vo(NOM) −5%
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 5 and 2 for the micro SMD package, is 1 kV.
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 temperture is calculated using:
A
Where the value of θ
for the SOT-23 package is 220˚C/W in a typical PC board mounting and the micro SMD package is 225˚C/W. Exceeding the maximum
J-A
allowable 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 LP2985 output must be diode-clamped to ground.
Note 5: The output PNP structure contains a diode between the V to V
terminals that is normally reverse-biased. Reversing the polarity from V to V
will
IN
OUT
IN
OUT
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: 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: The ON/OFF input must be properly driven to prevent possible misoperation. For details, refer to Application Hints.
>
Note 9: The LP2985 has foldback current limiting which allows a high peak current when V
0.5V, and then reduces the maximum output current as V
is
OUT
OUT
forced to ground (see Typical Performance Characteristics curves).
7
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Typical Performance Characteristics Unless otherwise specified: CIN = 1µF, COUT = 4.7µF, VIN
=
V
OUT(NOM) +1, TA = 25˚C, ON/OFF pin is tied to VIN.
VOUT vs Temperature
Short-Circuit Current
10014009
10014008
Short-Circuit Current
Short Circuit Current vs Output Voltage
10014010
10014011
Ripple Rejection
Ripple Rejection
10014013
10014014
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8
Typical Performance Characteristics Unless otherwise specified: CIN = 1µF, COUT = 4.7µF, VIN
=
V
OUT(NOM) +1, TA = 25˚C, ON/OFF pin is tied to VIN. (Continued)
Ripple Rejection
Ripple Rejection
Ripple Rejection
Ripple Rejection
10014015
10014016
10014018
10014023
Ripple Rejection
10014017
Ripple Rejection
10014019
9
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Typical Performance Characteristics Unless otherwise specified: CIN = 1µF, COUT = 4.7µF, VIN
=
V
OUT(NOM) +1, TA = 25˚C, ON/OFF pin is tied to VIN. (Continued)
Ripple Rejection
Output Impedance vs Frequency
10014020
10014022
Output Impedance vs Frequency
Output Noise Density
10014024
10014021
Output Noise Density
Ground Pin vs Load Current
10014025
10014026
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10
Typical Performance Characteristics Unless otherwise specified: CIN = 1µF, COUT = 4.7µF, VIN
=
V
OUT(NOM) +1, TA = 25˚C, ON/OFF pin is tied to VIN. (Continued)
Dropout Voltage vs Temperature
Input Current vs Pin
10014027
10014029
GND Pin Current vs Temperature
Instantaneous Short Circuit Current
10014031
10014030
Load Transient Response
Load Transient Response
10014032
10014033
11
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Typical Performance Characteristics Unless otherwise specified: CIN = 1µF, COUT = 4.7µF, VIN
=
V
OUT(NOM) +1, TA = 25˚C, ON/OFF pin is tied to VIN. (Continued)
Load Transient Response
Line Transient Response
Line Transient Response
Turn-On Time
10014035
10014034
Line Transient Response
10014036
10014037
Line Transient Response
10014038
10014039
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12
Typical Performance Characteristics Unless otherwise specified: CIN = 1µF, COUT = 4.7µF, VIN
=
V
OUT(NOM) +1, TA = 25˚C, ON/OFF pin is tied to VIN. (Continued)
Turn-On Time
Turn-On Time
10014041
10014040
Turn-On Time
10014042
13
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Application Hints
EXTERNAL CAPACITORS
ceramic capacitors can exhibit large changes in capacitance
with temperature (see next section, Capacitor Characteris-
tics).
Like any low-dropout regulator, the LP2985 requires external
capacitors for regulator stability. These capacitors must be
correctly selected for good performance.
The output capacitor must be located not more than 1 cm
from the output pin and returned to a clean analog ground.
Input Capacitor
Noise Bypass Capacitor:
An input capacitor whose capacitance is ≥ 1 µF is required
between the LP2985 input and ground (the amount of ca-
pacitance may be increased without limit).
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 cir-
cuit in the bandgap reference.
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.
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.
Important: Tantalum capacitors can suffer catastrophic fail-
ure 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.
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.
There are no requirements for ESR on the input capacitor,
but tolerance and temperature coefficient must be consid-
ered when selecting the capacitor to ensure the capacitance
will be ≥ 1 µF over the entire operating temperature range.
Output Capacitor:
CAPACITOR CHARACTERISTICS
The LP2985 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 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 LP2985 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 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 2.2 µF ceramic
capacitor is in the range of 10 mΩ to 20 mΩ, which easily
meets the ESR limits required for stability by the LP2985.
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).
One disadvantage of ceramic capacitors is that their capaci-
tance 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 2.2 µF capacitor were used
on the output since it will drop down to approximately 1 µF at
high ambient temperatures (which could cause the LM2985
to oscillate). If Z5U or Y5V capacitors are used on the output,
a minimum capacitance value of 4.7 µF must be observed.
A better choice for temperature coefficient in ceramic capaci-
±
tors is X7R, which holds the capacitance within 15%. Un-
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.
10014007
Important: The output capacitor must maintain its ESR
within the stable region over the full operating temperature
range of the application to assure stability.
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.
The LP2985 requires a minimum of 2.2 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
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.
www.national.com
14
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 LP2985 to 0.3V (see Absolute
Maximum Ratings).
Application Hints (Continued)
ON/OFF INPUT OPERATION
The LP2985 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 VIN to keep the regulator
output on at all times.
Micro SMD Mounting
The micro SMD package requires specific mounting tech-
niques which are detailed in National Semiconductor Appli-
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 VON/OFF. To prevent
mis-operation, the turn-on (and turn-off) voltage signals ap-
plied to the ON/OFF input must have a slew rate which is
≥ 40 mV/µs.
#
cation Note 1112. Referring to the section Surface Mount
Technology (SMT) Assembly Considerations, it should be
noted that the pad style which must be used with the 5-pin
package is the NSMD (non-solder mask defined) type.
For best results during assembly, alignment ordinals on the
PC board may be used to facilitate placement of the micro
SMD device.
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 VON/OFF (see Electri-
cal Characteristics).
Micro SMD Light Sensitivity
Exposing the micro SMD device to direct sunlight will cause
misoperation of the device. Light sources such as Halogen
lamps can also affect electrical performance if brought near
to the device.
REVERSE INPUT-OUTPUT VOLTAGE
The PNP power transistor used as the pass element in the
LP2985 has an inherent diode connected between the regu-
lator output and input. During normal operation (where the
input voltage is higher than the output) this diode is
reverse-biased.
The wavelenghts which have the most detrimental effect are
reds and infra-reds, which means that the fluorescent light-
ing used inside most buildings has very little effect on per-
formance. A micro SMD test board was brought to within 1
cm of a fluorescent desk lamp and the effect on the regu-
lated output voltage was negligible, showing a deviation of
less than 0.1% from nominal.
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.
15
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Physical Dimensions inches (millimeters)
unless otherwise noted
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
16
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
micro SMD, 5 Bump, Package (BPA05)
NS Package Number BPA05A
For Order Numbers, refer to Table 1 in the “Ordering Information” section of this document.
The dimensions for X1, X2 and X3 are as given:
X1 = 0.930 +/− 0.030mm
X2 = 1.107 +/− 0.030mm
X3 = 0.850 +/− 0.050mm
NOTES: UNLESS OTHERWISE SPECIFIED
1. EPOXY COATING
2. 63Sn/37Pb EUTECTIC BUMP
3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
4. PIN 1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. REMAINING PINS ARE NUMBERED COUNTER
CLOCKWISE.
5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS
PACKAGE HEIGHT.
6.NO JEDEC REGISTRATION AS OF AUG.1999.
17
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
micro SMD, 5 Bump, Package (BLA05 - 300 µm ball)
NS Package Number BLA05A
For Order Numbers, refer to Table 1 “Ordering Information” section of this document.
The dimensions for X1, X2 and X3 are as given:
X1 = 1.057 +/− 0.030mm
X2 = 1.412 +/− 0.030mm
X3 = 0.945 +/− 0.100mm
NOTES: UNLESS OTHERWISE SPECIFIED
1. EPOXY COATING
2. 63Sn/37Pb EUTECTIC BUMP
3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
4. PIN 1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. REMAINING PINS ARE NUMBERED COUNTER
CLOCKWISE.
5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS
PACKAGE HEIGHT.
6.NO JEDEC REGISTRATION AS OF AUG.1999.
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.
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
Corporation
Americas
National Semiconductor
Europe
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
Fax: +49 (0) 180-530 85 86
Email: support@nsc.com
Email: europe.support@nsc.com
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English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
Email: ap.support@nsc.com
www.national.com
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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