MIC2954 Datasheet, PDF (1/12 Pages) Micrel Semiconductor – 250mA Low-Dropout Regulator

MIC2954
Micrel
MIC2954
250mA Low-Dropout Regulator
General Description
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 typi-
cal). The quiescent current of the MIC2954 increases only
slightly in dropout, thus prolonging battery life. Key MIC2954
features include protection against reversed battery, fold-
back 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 pro-
grammed 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).
Features
• 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
• Battery powered equipment
• Cellular telephones
• Laptop, notebook, and palmtop computers
• PCMCIA V_CC and V_PP regulation/switching
• Bar code scanners
• Automotive electronics
• SMPS post-regulator/dc-to-dc modules
• Voltage reference
• High-efficiency linear power supplies
Typical Applications
MIC2954
V_IN
IN
OUT
GND
V_OUT
2.2µF
5V Fixed Regulator
100k
MIC2954
V_IN
8 _IN
OUT ¹
SHUTDOWN
ENABLE
3 _{SHDN ERR} 5
FB ⁷
GND
100pF
V_OUT = V_REF ^{}1+ _RR21^{}
4 _VREF
2, 6 = OPEN
V_ERR
V_OUT
1.2V to 30V
R1
10µF
R2
V_{IN MIC2954-07/-08}
+7V
8 _IN
OUT ¹
100pF
V_OUT
5V or 3.3V
SHUTDOWN
ENABLE
3 _{SHDN ERR} 5
FB ⁷
300k
1%
3.3µF
GND
4
220k
1%
180k
1%
5V
3.3V
470k
Q1
Q1 ON = 3.3V
Q1 OFF = 5.0V
2N2222
5V or 3V Selectable Regulator with Shutdown
Adjustable Regulator
MIC2954-07/-08
V_{IN 8 IN}
OUT ¹
SHUTDOWN
ENABLE
3 _{SHDN ERR} 5
FB ⁷
GND
4
V_OUT ≈ V_IN*
* MINIMUM INPUT-TO-OUTPUT
VOLTAGE RANGES FROM
40mV TO 400mV DEPENDING
UPON LOAD CURRENT
Wide Input-Voltage-Range Current Limiter
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
August 1999
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MIC2954