LP2951-03YM [MICREL]
100mA Low-Dropout Voltage Regulator; 100mA时的低压差稳压器
| 型号： | LP2951-03YM |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 100mA Low-Dropout Voltage Regulator |
| 文件： | 总17页 (文件大小：924K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LP2950*/2951
100mA Low-Dropout Voltage Regulator
General Description
Features
The LP2950 and LP2951 are micropower voltage
regulators with very low dropout voltage (typically 40mV at
light loads and 380mV at 100mA), and very low quiescent
current (75A typical). The quiescent current of the LP2950
/LP2951 increases only slightly in dropout, thus prolonging
battery life. This feature, among others, makes the LP2950
and LP2951 ideally suited for use in battery-powered
systems.
• High accuracy 5V, guaranteed 100mA output
• Extremely low quiescent current
• Low-dropout voltage
• Extremely tight load and line regulation
• Very low temperature coefficient
• Use as regulator or reference
• Needs only 1µF for stability
Available in a 3-pin TO-92 package, the LP2950 is pin-
compatible with the older 5V regulators. Additional system
functions, such as programmable output voltage and logic-
controlled shutdown, are available in the 8-pin DIP and 8-
pin SOIC versions of the LP2951.
LP2951 Versions Only
• Current and thermal limiting
• Error flag warns of output dropout
• Logic-controlled electronic shutdown
• Output programmable from 1.24 to 29V
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Applications
• Automotive electronics
• Voltage reference
• Avionics
___________________________________________________________________________________________________________
Block Diagram
LP2590 and LP2951 Block Diagram
(Pin Numbers Refer to LP2591)
* LP2950 Discontinuance September 2007.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-091208
September 2008
Micrel, Inc.
LP2950/2951
Additional features available with the LP2951 also
include an error flag output that warns of a low output
voltage, which is often due to failing batteries on the
input. This may also be used as a power-on reset. A
logic-compatible shutdown input is also available which
enables the regulator to be switched on and off. This
part may also be pin-strapped for a 5V output, or
programmed from 1.24V to 29V with the use of two
external resistors.
temperatures from –40°C to +125°C; the -02 version has
a tighter output and reference voltage specification
range over temperature. The LP2951 is available as an
-02 or -03 version.
The LP2950 and LP2951 have a tight initial tolerance
(0.5% typical), a very low output voltage temperature
coefficient which allows use as a low-power voltage
reference, and extremely good load and line regulation
(0.05% typical). This greatly reduces the error in the
overall circuit, and is the result of careful design
techniques and process control.
The LP2950 is available as either a -02 or -03 version.
The -02 and -03 versions are guaranteed for junction
___________________________________________________________________________________________________________
Ordering Information
Part Number
Voltage
Accuracy
Junction
Package
Lead Finish
Temperature Range
LP2950-02BZ*
LP2950-03BZ*
LP2951-02BM
LP2951-03BM
LP2951-02BN
LP2951-03BN**
LP2951-02YM
LP2951-03YM
LP2951-02YN
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
5.0V
0.5%
1.0%
0.5%
1.0%
0.5%
1.0%
0.5%
1.0%
0.5%
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
–40° to +125°C
3-Pin TO-92 Plastic
3-Pin TO-92 Plastic
8-Pin SOIC
Standard
Standard
Standard
Standard
Standard
Standard
Pb-Free
Pb-Free
Pb-Free
8-Pin SOIC
8-Pin Plastic DIP
8-Pin Plastic DIP
8-Pin SOIC
8-Pin SOIC
8-Pin Plastic DIP
Note:
*
TO-92 Package discontinuance notification issued September 2007. End-of-life-buy offer thru December 31, 2007. Contact factory for
additional information.
** Contact factory for Pb-Free version.
Pin Configuration
TO-92 (Z)
DIP (N) and SOIC (M)
(Bottom View)
See MIC2950 for a part with: 1) higher output (150mA), 2) transient protection (60V), and 3) reverse input protection to –20V.
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Micrel, Inc.
LP2950/2951
Absolute Maximum Ratings(1)
If Military/Aerospace specified devices are required,
contact your local Micrel representative/distributor for
availability and specifications.
Power Dissipation .....................................Internally Limited
Lead Temperature (soldering, 5 sec.)........................ 260°C
Storage Temperature................................–65°C to +150°C
Operating Junction Temperature Range(8)
LP2950, LP2951.................................–40°C to +125°C
Input Supply Voltage........................................–0.3 to +30V
Feedback Input Voltage(9, 10) ............................–1.5 to +30V
Shutdown Input Voltage(9) ................................–0.3 to +30V
Error Comparator Output Voltage(9) .................–0.3 to +30V
ESD Rating is to be determined
Electrical Characteristics(1)
TA = 25°C except as noted.
Parameter
Condition
Min
Typ
Max
Units
Output Voltage
TJ = 25°C
LP295x-02 (±0.5%)
4.975
4.950
4.802
4.950
4.925
4.777
4.940
4.900
4.753
4.930
4.880
4.733
5.000
5.000
4.850
5.025
5.050
4.899
5.050
5.075
4.872
5.060
5.100
4.947
5.070
5.120
4.967
100
V
LP295x-03 (±1%)
V
LP2951-4.8 (±1%)
V
Output Voltage
–25°C ≤ TJ ≤ +85°C
LP295x-02 (±0.5%)
V
LP295x-03 (±1%)
V
LP2951-4.8 (±1%)
V
Output Voltage
Over Full Temperature Range
–40°C to +125°C
LP295x-02 (±0.5%)
V
LP295x-03 (±1%)
V
LP2951-4.8 (±1%)
V
V
Output Voltage
Over Load Variation
LP295x-02 (±0.5%), 100µA ≤ IL ≤ 100mA, TJ ≤ TJ(max)
LP295x-03 (±1%), 100µA ≤ IL ≤ 100mA, TJ ≤ TJ(max)
LP2951-4.8 (±1%), 100µA ≤ IL ≤ 100mA, TJ ≤ TJ(max)
LP295x-02 (±0.5%), Note 12
LP295x-03 (±1%), Note 12
LP2951-4.8 (±1%), Note 12
LP295x-02 (±0.5%), Notes 14, 15
V
V
Output Voltage
Temperature Coefficient
20
50
ppm/°C
ppm/°C
ppm/°C
150
50
150
Line Regulation
0.03
0.10
0.20
%
%
LP295x-03 (±1%), Notes 14, 15
0.04
0.04
0.04
0.10
0.10
0.20
0.40
%
%
LP2951-4.8 (±1%), Notes 14, 15
0.20
0.40
%
%
Load Regulation
LP295x-02 (±0.5%), Note 14, 100µA ≤ IL ≤ 100mA
LP295x-03 (±1%), Note 14, 100µA ≤ IL ≤ 100mA
LP2951-4.8 (±1%), Note 14, 100µA ≤ IL ≤ 100mA
0.10
0.20
%
%
0.20
0.30
%
%
0.20
0.30
%
%
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LP2950/2951
Parameter
Condition
Min
Typ
Max
Units
Dropout Voltage
Note 5, IL = 100µA
50
80
150
mV
mV
Note 5, IL = 100mA
IL = 100µA
380
100
8
450
600
mV
mV
Ground Current
150
200
µA
µA
IL = 100mA
12
14
mA
mA
Dropout Current
Current Limit
VIN = 4.5V, IL = 100µA
VOUT = 0V
180
160
250
310
µA
µA
220
220
mA
mA
Thermal Regulation
Output Noise
Note 13
0.05
430
160
100
0.20
%/W
µVRMS
µVRMS
µVRMS
10Hz to 100kHz, CL = 1µF
10Hz to 100kHz, CL = 200µF
10Hz to 100kHz, CL = 3.3µF,
0.01µF bypass Feedback to Output
Reference Voltage
Reference Voltage
LP295x-02 (±0.5%)
LP295x-03 (±1%)
LP2951-4.8 (±1%)
1.220
1.200
1.235
1.235
1.235
1.250
1.260
V
V
1.210
1.200
1.260
1.270
V
V
1.210
1.200
1.260
1.270
V
V
LP295x-02 (±0.5%), Note 7
LP295x-03 (±1%), Note 7
LP2951-4.8 (±1%), Note 7
1.190
1.185
1.185
1.270
1.285
1.285
V
V
V
Feedback Bias Current
Reference Voltage
20
40
60
nA
nA
LP295x-02 (±0.5%), Note 12
LP295x-03 (±1%), Note 12
LP2951-4.8 (±1%), Note 12
20
50
50
0.1
ppm/°C
ppm/°C
ppm/°C
nA/°C
Feedback Bias Current
Temperature Coefficient
Output Leakage Current
Output Low Voltage (Flag)
Upper Threshold Voltage
Lower Threshold Voltage
Hysteresis
VOH = 30V
VIN = 4.5V, IOL = 200µA
Note 6
0.01
150
60
1.00
2.00
µA
µA
250
400
mV
mV
40
25
mV
mV
Note 6
75
95
140
mV
mV
Note 6
15
mV
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Micrel, Inc.
LP2950/2951
Parameter
Condition
Min
2.0
2.0
2.0
Typ
Max
Units
Input Logic Voltage
LP295x-02 (±0.5%)
Low
High
1.3
V
V
V
0.7
0.7
0.7
LP295x-03 (±1%)
Low
High
1.3
1.3
V
V
V
LP2951-4.8 (±1%)
Low
High
V
V
V
Shutdown Input Current
VSHUTDOWN = 2.4V
30
450
3
50
100
µA
µA
VSHUTDOWN = 30V
600
700
µA
µA
Regulator Output Current
in Shutdown
Note 11
10
20
µA
µA
Notes:
1. Boldface limits apply at temperature extremes.
2. Unless otherwise specified all limits guaranteed for TJ = 25°C, VIN = 6V, IL = 100µA and CL = 1µF. Additional conditions for the 8-pin versions are
Feedback tied to 5V Tap and Output tied to Output Sense (VOUT = 5V) and VSHUTDOWN ≤ 0.8V.
3. Guaranteed and 100% production tested.
4. Guaranteed but not 100% production tested. These limits are not used to calculate outgoing AQL levels.
5. Dropout voltage is defined as the input to output differential at which the output voltage drops 100mV below its nominal value measured at 1V
differential. At very low values of programmed output voltage, the minimum input supply voltage of 2V (2.3V over temperature) must be taken into
account.
6. Comparator thresholds are expressed in terms of a voltage differential at the Feedback terminal below the nominal reference voltage measured at
6V input. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = VOUT /VREF =(R1 + R2)/R2. For
example, at a programmed output voltage of 5V, the Error output is guaranteed to go low when the output drops by 95mV x 5V/1.235V = 384mV.
Thresholds remain constant as a percent of VOUT as VOUT is varied, with the dropout warning occurring at typically 5% below nominal, 7.5%
guaranteed.
7. VREF ≤ VOUT ≤ (VIN – 1 V), 2.3V ≤ VIN ≤ 30V, 100µA < IL ≤ 100mA, TJ ≤ TJMAX
.
8. The junction-to-ambient thermal resistance of the TO-92 package is 180°C/W with 0.4” leads and 160°C/W with 0.25” leads to a PC board. The
thermal resistance of the 8-pin DIP package is 105°C/W junction-to-ambient when soldered directly to a PC board. Junction-to-ambient thermal
resistance for the SOIC (M) package is 160°C/W.
9. May exceed input supply voltage.
10. When used in dual-supply systems where the output terminal sees loads returned to a negative supply, the output voltage should be diode-clamped
to ground.
11. VSHUTDOWN ≥ 2V, VIN ≤ 30 V, VOUT = 0, with Feedback pin tied to 5V Tap.
12. Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
13. Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 50mA load pulse at VIN = 30V (1.25W pulse) for t = 10ms.
14. Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage due to heating
effects are covered in the specification for thermal regulation.
15. Line regulation for the LP2951 is tested at 150°C for IL = 1mA. For IL = 100µA and TJ = 125°C, line regulation is guaranteed by design to 0.2%. See
Typical Performance Characteristics for line regulation versus temperature and load current.
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Micrel, Inc.
LP2950/2951
Typical Characteristics
M9999-091208
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Micrel, Inc.
LP2950/2951
Typical Characteristics (continued)
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LP2950/2951
Typical Characteristics (continued)
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Micrel, Inc.
LP2950/2951
Figure 1 is a timing diagram depicting the /ERROR
signal and the regulated output voltage as the LP2951
input is ramped up and down. The /ERROR signal
becomes valid (low) at about 1.3V input. It goes high at
about 5V input (the input voltage at which VOUT = 4.75V).
Since the LP2951’s dropout voltage is load-dependent
(see curve in Typical Performance Characteristics), the
input voltage trip point (about 5V) will vary with the load
current. The output voltage trip point (approximately
4.75V) does not vary with load.
Application Information
External Capacitors
A 1.0µF (or greater) capacitor is required between the
LP2950/LP2951 output and ground to prevent
oscillations due to instability. Most types of tantalum or
aluminum electrolytics will be adequate; film types will
work, but are costly and therefore not recommended.
Many aluminum electrolytics have electrolytes that
freeze at about –30°C, so solid tantalum capacitors are
recommended for operation below –25°C. The important
parameters of the capacitor are an effective series
resistance of about 5 or less and a resonant frequency
above 500kHz. The value of this capacitor may be
increased without limit.
The error comparator has an open-collector output which
requires an external pull-up resistor. Depending on
system requirements, this resistor may be returned to
the 5V output or some other supply voltage. In
determining a value for this resistor, note that while the
output is rated to sink 400µA, this sink current adds to
battery drain in a low battery condition. Suggested
values range from 100k to 1MΩ. The resistor is not
required if this output is unused.
At lower values of output current, less output
capacitance is required for output stability. The capacitor
can be reduced to 0.33µF for current below 10mA or
0.1µF for currents below 1mA. Using the 8-pin versions
at voltages below 5V runs the error amplifier at lower
gains so that more output capacitance is needed. For
the worst-case situation of a 100mA load at 1.23V output
(Output shorted to Feedback) a 3.3µF (or greater)
capacitor should be used.
Programming the Output Voltage (LP2951)
The LP2951 may be pin-strapped for 5V using its
internal voltage divider by tying Pin 1 (output) to Pin 2
(SENSE) and Pin 7 (FEEDBACK) to Pin 6 (5V TAP).
Alternatively, it may be programmed for any output
voltage between its 1.235V reference and its 30V
maximum rating. An external pair of resistors is required,
as shown in Figure 2.
The LP2950 will remain stable and in regulation with no
load in addition to the internal voltage divider, unlike
many other voltage regulators. This is especially
important in CMOS RAM keep-alive applications. When
setting the output voltage of the LP2951 version with
external resistors, a minimum load of 1µA is recomm-
ended.
The complete equation for the output voltage is:
⎧
⎫
⎬
⎭
R1
R2
VOUT = VREF × 1+
+ IFB R2
⎨
⎩
A
0.1µF capacitor should be placed from the
LP2950/LP2951 input to ground if there is more than 10
inches of wire between the input and the AC filter
capacitor or if a battery is used as the input.
where VREF is the nominal 1.235 reference voltage and
IFB is the feedback pin bias current, nominally 20nA. The
minimum recommended load current of 1µA forces an
upper limit of 1.2MΩ on the value of R2, if the regulator
must work with no load (a condition often found in
CMOS in standby), IFB will produce a 2% typical error in
VOUT which may be eliminated at room temperature by
trimming R1. For better accuracy, choosing R2 = 100kΩ
reduces this error to 0.17% while increasing the resistor
program current to 12µA. Since the LP2951 typically
draws 60µA at no load with Pin 2 open-circuited, this is a
small price to pay.
Stray capacitance to the LP2951 Feedback terminal (pin
7) can cause instability. This may especially be a
problem when using high value external resistors to set
the output voltage. Adding a 100pF capacitor between
Output and Feedback and increasing the output
capacitor to at least 3.3µF will remedy this.
Error Detection Comparator Output
A logic low output will be produced by the comparator
whenever the LP2951 output falls out of regulation by
more than approximately 5%. This figure is the
comparator’s built-in offset of about 60mV divided by the
1.235V reference voltage. (Refer to the block diagram on
Page 1). This trip level remains “5% below normal”
regardless of the programmed output voltage of the
LP2951. For example, the error flag trip level is typically
4.75V for a 5V output or 11.4V for a 12V output. The out
of regulation condition may be due either to low input
voltage, current limiting, or thermal limiting.
Reducing Output Noise
In reference applications it may be advantageous to
reduce the AC noise present at the output. One method
is to reduce the regulator bandwidth by increasing the
size of the output capacitor. This is the only method by
which noise can be reduced on the 3-pin LP2950 and is
relatively inefficient, as increasing the capacitor from 1µF
to 220µF only decreases the noise from 430µV to
160µVrms for a 100kHz bandwidth at 5V output.
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Micrel, Inc.
LP2950/2951
Noise can be reduced fourfold by a bypass capacitor
across R1, since it reduces the high frequency gain from
4 to unity. Pick:
1
CBYPASS
≅
2πR1 • 200Hz
or about 0.01µF. When doing this, the output capacitor
must be increased to 3.3µF to maintain stability. These
changes reduce the output noise from 430µV to
100µVrms for a100kHz bandwidth at 5V output. With the
bypass capacitor added, noise no longer scales with
output voltage so that improvements are more dramatic
at higher output voltages.
Figure 1. ERROR Output Timing
Figure 2. Adjustable Regulator
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Micrel, Inc.
LP2950/2951
Typical Applications
Wide Input Voltage Range Current Limiter
5V Regulator with 2.5V Sleep Function
Low Drift Current Source
5V Current Limiter
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Micrel, Inc.
LP2950/2951
Typical Applications
Regulator with Early Warning and Auxiliary Output
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Micrel, Inc.
LP2950/2951
Typical Applications
Latch Off When Error Flag Occurs
Open Circuit Detector for 4mA to 20mA Current Loop
Regulator with State-of-Charge Indicator
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Micrel, Inc.
LP2950/2951
Typical Applications
Low Battery Disconnect
System Over Temperature Protection Circuit
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Micrel, Inc.
LP2950/2951
Schematic Diagram
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Micrel, Inc.
LP2950/2951
Package Information
8-Pin SOIC (M)
PIN 1
DIMENSIONS:
INCH (MM)
0.380 (9.65)
0.370 (9.40)
0.255 (6.48)
0.245 (6.22)
0.135 (3.43)
0.125 (3.18)
0.300 (7.62)
0.013 (0.330)
0.010 (0.254)
0.380 (9.65)
0.320 (8.13)
0.018 (0.57)
0.100 (2.54)
0.130 (3.30)
0.0375 (0.952)
8-Pin Plastic DIP (N)
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Micrel, Inc.
LP2950/2951
0.090 (2.286) Radius, typ.
1
2
3
0.145 (3.683)
0.135 (3.429)
0.055 (1.397)
0.045 (1.143)
10° typ.
BOTTOM VIEW
0.085 (2.159) Diam.
0.185 (4.699)
0.175 (4.445)
5° typ.
5° typ.
0.185 (4.699)
0.175 (4.445)
0.090 (2.286) typ.
Seating Plane
0.025 (0.635) Max
Uncontrolled
Lead Diameter
0.500 (12.70) Min.
0.016 (0.406)
0.014 (0.356)
0.0155 (0.3937)
0.0145 (0.3683)
0.055 (1.397)
0.045 (1.143)
0.105 (2.667)
0.095 (2.413)
TO-92 (Z)
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 1999 Micrel, Incorporated.
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