MIC2954
Micrel
MIC2954
250mA Low-Dropout Regulator
Final Information
General Description
Features
The MIC2954 is a “bulletproof” efficient voltage regulator with
very low dropout voltage (typically 40mV at light loads and
375mV at 250mA), and low quiescent current (120µA typical). The quiescent current of the MIC2954 increases only
slightly in dropout, thus prolonging battery life. Key MIC2954
features include protection against reversed battery, foldback current limiting, and automotive load dump protection
(60V positive transient).
The MIC2954-07/08BM is an adjustable version that includes
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 provided which enables the regulator to be switched on and
off. This part may be pin-strapped for 5V output, or programmed from 1.24V to 29V with the use of two external
resistors.
The MIC2954 is available in two voltage tolerances, ±0.5%
maximum and ±1% maximum. Both are guaranteed for
junction temperatures from –40°C to +125°C.
The MIC2954 has a very low output voltage temperature
coefficient and extremely good load and line regulation
(0.04% typical).
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High-accuracy 5V, guaranteed 250mA output
Low quiescent current
Low dropout voltage
Extremely tight load and line regulation
Very low temperature coefficient
Current and thermal limiting
Input can withstand –20V reverse battery and
+60V positive transients
Error flag warns of low output voltage
Logic-controlled electronic shutdown
Output programmable from 1.24V to 29V
(MIC2954-07/08)
Available in TO-220, TO-92, and surface-mount
SOT-223 and SOP-8 packages
Applications
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Battery powered equipment
Cellular telephones
Laptop, notebook, and palmtop computers
PCMCIA VCC and VPP regulation/switching
Bar code scanners
Automotive electronics
SMPS post-regulator/dc-to-dc modules
Voltage reference
High-efficiency linear power supplies
Typical Applications
100k
VIN
MIC2954
IN
VOUT
8
IN
OUT
SHDN ERR
3
GND
SHUTDOWN
ENABLE
2.2µF
FB
1
R1
VOUT = VREF 1 +
R2
4
R1
5
7
GND
5V Fixed Regulator
VOUT
1.2V to 30V
MIC2954
VIN
OUT
VERR
100pF
VREF
10µF
R2
2, 6 = OPEN
Adjustable Regulator
VIN MIC2954-07/-08
+7V 8
1
IN
OUT
3
SHDN ERR
FB
7
GND
4
5V
3.3V
100pF
5
SHUTDOWN
ENABLE
VOUT
5V or 3.3V
220k
1%
300k
1%
VIN
180k
1%
IN
OUT
1
3
3.3µF
SHDN ERR
5
FB
7
SHUTDOWN
ENABLE
VOUT ≈ VIN*
* MINIMUM INPUT-TO-OUTPUT
VOLTAGE RANGES FROM
40mV TO 400mV DEPENDING
UPON LOAD CURRENT
GND
470k
Q1 ON = 3.3V
Q1 OFF = 5.0V
MIC2954-07/-08
8
4
Q1
2N2222
Wide Input-Voltage-Range Current Limiter
5V or 3V Selectable Regulator with Shutdown
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
August 1999
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MIC2954
