|
|
PDF MIC2951 Data sheet ( Hoja de datos )
| Número de pieza | MIC2951 | |
| Descripción | 150mA Low-Dropout Voltage Regulator | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MIC2951 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
|
No Preview Available !
MIC2950*/2951
150mA Low-Dropout Voltage Regulator
General Description
Features
The MIC2950 and MIC2951 are “bulletproof” micropower
voltage regulators with very low dropout voltage (typically
40mV at light loads and 250mV at 100mA), and very low
quiescent current. Like their predecessors, the LP2950 and
LP2951, the quiescent current of the MIC2950/MIC2951
increases only slightly in dropout, thus pro-longing battery
life. The MIC2950/MIC2951 are pin for pin compatible with
the LP2950/LP2951, but offer lower dropout, lower
quiescent current, reverse battery, and automotive load
dump protection.
The key additional features and protection offered include
higher output current (150mA), positive transient protection
for up to 60V (load dump), and the ability to survive an
unregulated input voltage transient of –20V below ground
(reverse battery).
The plastic DIP and SOIC versions offer additional system
functions such as programmable output voltage and logic
controlled shutdown. The 3-pin TO-92 MIC2950 is pin-
compatible with the older 5V regulators.
These system functions 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 5 V output, or
programmed from 1.24 V to 29 V with the use of two
external resistors.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
• High accuracy 3.3, 4.85, or 5V, guaranteed 150mA
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 1.5µF for stability
• Current and thermal limiting
• Unregulated DC input can withstand –20V reverse
battery and +60V positive transients
MIC2951 Version Only
• Error flag warns of output dropout
• Logic-controlled electronic shutdown
• Output programmable from 1.24 to 29V
Applications
• Automotive electronics
• Voltage reference
• Avionics
• Cellular telephones
• Battery powered equipment
• SMPS post-regulator
• High efficiency linear power supplies
___________________________________________________________________________________________________________
Block Diagram
* MIC2950 Discontinuance September 2007.
MM8 is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
February 2010
M9999-021610
1 page  
Micrel, Inc.
MIC2950/2951
Parameter
Load Regulation
Dropout Voltage
Ground Current
Dropout Ground Current
Condition
MIC295x-02/-05 (±0.5%), 100µA ≤ IL ≤ 150mA, Note 10
MIC295x-03/-06 (±1%), 100µA ≤ IL ≤ 150mA, Note 10
MIC2951-3.3 (±1%), 100µA ≤ IL ≤ 150mA, Note 10
MIC2951-4.8 (±1%), 100µA ≤ IL ≤ 150mA, Note 10
MIC295x-02/-03/-05/-06, IL = 100µA, Note 12
MIC295x-02/-03/-05/-06, IL = 100mA, Note 12
MIC295x-02/-03/-05/-06, IL = 150mA, Note 12
MIC2951-3.3 (±1%), IL = 100µA, Note 12
MIC2951-3.3 (±1%), IL = 100mA, Note 12
MIC2951-3.3 (±1%), IL = 150mA, Note 12
MIC2951-4.8 (±1%), IL = 100µA, Note 12
MIC2951-4.8 (±1%), IL = 100mA, Note 12
MIC2951-4.8 (±1%), IL = 150mA, Note 12
MIC295x-02/-03/-05/-06, IL = 100µA
MIC295x-02/-03/-05/-06, IL = 100mA
MIC295x-02/-03/-05/-06, IL = 150mA
MIC2951-3.3 (±1%), IL = 100µA
MIC2951-3.3 (±1%), IL = 100mA
MIC2951-3.3 (±1%), IL = 150mA
MIC2951-4.8 (±1%), IL = 100µA
MIC2951-4.8 (±1%), IL = 100mA
MIC2951-4.8 (±1%), IL = 150mA
MIC295x-02/-03/-05/-06, VIN = 4.5V, IL = 100µA
MIC2951-3.3 (±1%), VIN = 3.0V, IL = 100µA
MIC2951-4.8 (±1%), VIN = 4.3V, IL = 100µA
Min Typ Max
0.04 0.10
0.20
0.10 0.20
0.30
0.10 0.20
0.30
0.10 0.20
0.30
40 80
140
250 300
300 450
600
40 80
150
250 350
320 450
600
40 80
140
250 300
320 450
600
120 180
300
1.7 2.5
3.5
46
8
100 180
300
1.7 2.5
46
10
120 180
300
1.7 2.5
3.5
46
8
280 350
400
150 350
400
280 350
400
Units
%
%
%
%
%
%
%
%
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
mV
µA
µA
mA
mA
mA
mA
µA
µA
mA
mA
mA
µA
µA
mA
mA
mA
mA
µA
µA
µA
µA
µA
µA
February 2010
5 M9999-021610
5 Page 
Micrel, Inc.
MIC2950/2951
Application Information
Automotive Applications
The MIC2950/2951 are ideally suited for automotive
applications for a variety of reasons. They will operate
over a wide range of input voltages, have very low
dropout voltages (40mV at light loads), and very low
quiescent currents. These features are necessary for use
in battery powered systems, such as automobiles. They
are also “bulletproof” devices; with the ability to survive
both reverse battery (negative transients up to 20V below
ground), and load dump (positive transients up to 60V)
conditions. A wide operating temperature range with low
temperature coefficients is yet another reason to use
these versatile regulators in automotive designs
External Capacitors
A 1.5µF (or greater) capacitor is required between the
MIC2950/MIC2951 output and ground to prevent
oscillations due to instability. Most types of tantalum or
aluminum elec-trolytics 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 tantalums are recomm-ended for
operation below –25°C. The important parameters of the
capacitor are an effective series resistance of about 5Ω or
less and a resonant frequency above 500kHz. The value
of this capacitor may be increased without limit.
At lower values of output current, less output capacitance
is required for output stability. The capacitor can be
reduced to 0.5µF for current below 10mA or 0.15µF for
currents below 1 mA. 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 150mA load at 1.23V output (Output shorted
to Feedback) a 5µF (or greater) capacitor should be used.
The MIC2950 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 MIC2951 version with external
resistors, a minimum load of 1µA is recomm-ended.
A 0.1µF capacitor should be placed from the MIC2950/
MIC2951 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.
Stray capacitance to the MIC2951 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 MIC2951 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
MIC2951. 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, thermal limiting, or overvolt-age
on input (over ≅ 40V).
Figure 1 is a timing diagram depicting the /ERROR signal
and the regulated output voltage as the MIC2951 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 = 4.75—for 5.0V
applications). Since the MIC2951’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
does not vary with load.
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
output or some other supply voltage. In determining a
value for this resistor, note that while the output is rated to
sink 200µA, 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.
Programming the Output Voltage (MIC2951)
The MIC2951 may be pin-strapped for 5V (or 3.3V or
4.85V) 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 complete equation for the output voltage is:
VOUT
=
VREF
× ⎨⎧1 +
⎩
R1
R2
⎫
⎬
⎭
+
IFB
R1
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 = 100k reduces this
error to 0.17% while increasing the resistor program
current to 12µA.
February 2010
11 M9999-021610
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet MIC2951.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MIC2950 | 150mA Low-Dropout Voltage Regulator | Micrel Semiconductor |
| MIC2950-05BZ | 150mA Low-Dropout Voltage Regulator | Micrel Semiconductor |
| MIC2950-06BZ | 150mA Low-Dropout Voltage Regulator | Micrel Semiconductor |
| MIC29500 | High-Current Low-Dropout Regulators |  Micrel |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |