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 prolonging 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 pincompatible 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.
Features
•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
•Error flag warns of output dropout (MIC2951)
•Logic-controlled electronic shutdown (MIC2951)
•Output programmable from 1.24V to 29V (MIC2951)
Applications
•Automotive Electronics
•Battery Powered Equipment
•Cellular Telephones
•SMPS Post-Regulator
•Voltage Reference
•Avionics
•High Efficiency Linear Power Supplies
3
Block Diagram
Unregulated
DC Supply
SHDN
TTL/CMOS
Control Logic
Input
60mV
1.23V
REF.
MIC2951-0x
INFB
Error
Amp.
Error Detection
Comparator
182k
60k
OUT
SNS
TAP
ERR
GND
5V/150mA
Output
330k
TTL/CMOS
Compatible
Error Output
1.5µF
February 19993-49
MIC2950/2951Micrel
The MIC2950 is available as either an -05 or -06 version. The
-05 and -06 versions are guaranteed for junction temperatures
from –40°C to +125°C; the -05 version has a tighter output and
reference voltage specification range over temperature. The
MIC2951 is available as an -02 or -03 version.
Ordering Information
Part NumberVoltageAccuracy Temperature Range*Package
MIC2950-05BZ5.0V0.5%–40°C to +125°CTO-92
MIC2950-06BZ5.0V1.0%–40°C to +125°CTO-92
MIC2951-02BM5.0V0.5%–40°C to +125°C8-pin SOIC
MIC2951-03BM5.0V1.0%–40°C to +125°C8-pin SOIC
MIC2951-02BN5.0V0.5%–40°C to +125°C8-pin plastic DIP
MIC2951-03BN5.0V1.0%–40°C to +125°C8-pin plastic DIP
MIC2951-03BMM5.0V1.0%–40°C to +125°C8-lead MM8™
MIC2951-3.3BM3.3V1.0%–40°C to +125°C8-pin SOIC
MIC2951-4.8BM4.85V1.0%–40°C to +125°C8-pin SOIC
* junction temperature
The MIC2950 and MIC2951 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 (0.04% typical). This
greatly reduces the error in the overall circuit, and is the result
of careful design techniques and process control.
Pin Configuration
MIC2950-xx
321
OUT
GND
IN
TO-92 (Z)
(Bottom View)
Pin Description
Pin #Pin #Pin NamePin Function
MIC2950MIC2951
31OUTRegulated Output
2SNSSense (Input): Output-voltage sensing end of internal voltage divider for
fixed 5V operation. Not used in adjustable configuration.
3SHDNShutdown/Enable (Input): TTL compatible input. High = shutdown,
low or open = enable.
24GNDGround
5ERRError Flag (Output): Active low, open-collector output (low = error,
floating = normal).
6TAP3.3V/4.85/5V Tap: Output of internal voltage divider when the regulator is
configured for fixed operation. Not used in adjustable configuration.
7FBFeedback (Input): 1.235V feedback from internal voltage divider’s TAP (for
fixed operation) or external resistor network (adjustable configuration).
18INUnregulated Supply Input
MIC2951-xx
OUT
SNS
SHDN
GND
1
2
3
4
8
IN
7
FB
6
TAP
5
ERR
DIP (N), SOIC (M), MM8™ (MM)
(Top View)
3-50February 1999
MIC2950/2951Micrel
Absolute Maximum Ratings (Note 1)
Input Suppy Voltage (VIN) Note 5 ................. –20V to +60V
Feedback Input Voltage (VFB) Note 6, 7...... –1.5V to +26V
Shutdown Input Voltage (V
Power Dissipation (PD) Note 4 ................Internally Limited
) Note 6 ..... –0.3V to +30V
SHDN
Operating Ratings (Note 2)
Input Supply Voltage (VIN) ........................... +2.0V to +30V
Junction Temperature (TJ) ....................................... Note 4
MIC2950-05/MIC2950-06.....................–40°C to +125°C
MIC2951-02/MIC2950-03.....................–40°C to +125°C
Storage Temperature ..............................–65°C to + 150°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C