MIC2954
250mA Low-Dropout Regulator
General Description
The MIC2954 is a “bulletproof” efficient voltage regulator
with very low dropout voltage (typically 40mV @ light loads
and 375mV @ 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, 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 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.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
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 SOIC-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
___________________________________________________________________________________________________________
Ordering Information
Part Number
Pb-Free /
Standard
RoHS Compliant
MIC2954-02BT
MIC2954-02WT*
MIC2954-03BT
MIC2954-03WT*
MIC2954-02BS
MIC2954-02WS*
MIC2954-03BS
MIC2954-03WS*
MIC2954-02BZ
MIC2954-02YZ
MIC2954-03BZ
MIC2954-03YZ
MIC2954-07BM
MIC2954-07YM
MIC2954-08BM
MIC2954-08YM
Accuracy
0.5%
1.0%
0.5%
1.0%
0.5%
1.0%
0.5%
1.0%
Junction
Temp. Range
–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
Package
TO-220-3
TO-220-3
SOT-223-3
SOT-223-3
TO-92-3**
TO-92-3**
8-Pin SOIC
8-Pin SOIC
* RoHS compliant with ‘high-melting solder’ exemption.
** TO-92 package discontinuance notification issued September 2007. End-of-life-buy offered thru December 31, 2007.
Contact factory for additional information.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
September 2007
M9999-090607
Micrel, Inc.
MIC2954
Pin Configuration
OUT 1
SNS 2
SHDN 3
GND 4
8 IN
7 FB
6 TAP
5 ERR
1
IN
2
3
GND OUT
8-Pin SOIC (M)
3-Pin SOT-223 (S)
3
2
TO-92
1
OUT
3
TAB
OUT
GND
IN
GND
IN
2
1
3-Pin TO-220 (T)
3-Pin TO-92 (Z)
Pin Description
Pin No.
SOIC-8
8
4
1
2
Pin No.
SOT-223
1
2, TAB
3
Pin No.
TO-92
1
2
3
Pin No.
TO-220
1
2
3
Pin Name
IN
GND
OUT
SNS
Pin Name
Supply Input.
Ground.
Regulator Output.
Sense (Input): Output-sense-voltage end of internal resistive divider.
Connect to OUT (V
OUT
= 5V) for fixed5V operation; also see TAP.
Not used in adjustable configuration.
Shutdown (Input): Active-low input enables regulator.
(Low = enable; high = shutdown.)
Error Flag (Output): Open collector (active-low) output. Active state
indicates an output (V
OUT
) undervoltage condition.
(Low = error, floating = normal.)
Divider Tap (Output): Resistive voltage divider tap. With 5Vapplied to
SNS, VTAP is approximately 1.23V. Connect to FB for 5V operation.
Not used in adjustable configuration.
Feedback (Input): Error amplifier input. Compared to internal1.23V
reference. Connect to external voltage divider for adjustable operation
or internal voltage divider (TAP) for 5V operation (see SNS, TAP).
3
5
SHDN
/ERR
6
TAP
7
FB
September 2007
3
M9999-090607
Micrel, Inc.
MIC2954
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) ....................................... –20V to +60V
Feedback Voltage (V
FB
)
(14, 15)
........................ –1.5V to +26V
Shutdown Input Voltage (V
SHDN
).................... –0.3V to +30V
Error Output Voltage (V
ERR
) .......................... –0.3V to +30V
Power Dissipation (P
D
)
(4)
..........................Internally Limited
Lead Temperature (soldering, 5 sec.)........................ 260°C
Storage Temperature (T
s
) .........................–65°C to +150°C
ESD Rating
(3)
Operating Ratings
(2)
Supply Voltage (V
IN
)...................................... +2.0V to +30V
Junction Temperature (T
J
) ........................ –40°C to +125°C
Package Thermal Resistance (θ
JC
,
θ
JA
)
(5)
Electrical Characteristics
MIC2954-07/08: V
FB
= V
TAP
; V
SNS
= V
OUT
; V
SHDN
≤
0.6V. All versions: V
IN
= 6V; I
L
= 1mA; C
L
= 2.2µF; T
J
= 25°C,
bold
values indicate –40°C
≤
T
J
≤
+125°C;
Note 8;
unless noted.
Symbol
V
OUT
Parameter
Output Voltage
Condition
MIC2954-02/-07 (±0.5%)
MIC2954-02/-07 (±0.5%), 1mA
≤
I
L
≤
250mA
MIC2954-03/-08 (±1%)
MIC2954-03/-08 (±1%), 1mA
≤
I
L
≤
250mA
Min
4.975
4.940
Typ
5.000
Max
5.025
5.060
Units
V
V
V
V
V
V
ppm/°C
ppm/°C
%/V
%/V
%/V
%/V
%/V
%/V
%/V
%/V
mV
mV
mV
mV
mV
mV
mV
mV
µA
µA
mA
mA
mA
mA
mA
mA
µA
4.930
4.950
4.900
5.000
5.000
5.070
5.050
5.100
4.880
5.000
20
20
0.03
0.03
0.04
0.04
60
220
250
375
140
0.5
1.7
5
180
5.120
100
150
0.10
0.20
0.20
0.40
0.16
0.20
0.20
0.30
100
150
250
420
300
450
450
600
200
300
1
2
2.5
3.5
9
12
∆V
OUT
/∆T
∆V
OUT
/V
OUT
Output Voltage Temperature
Coefficient,
Note 6
Line Regulation,
Note 7
MIC2954-02/-07 (±0.5%)
MIC2954-03/-08 (±1%)
MIC2954-02/-07 (±0.5%), V
IN
= 6V to 26V
MIC2954-03/-08 (±1%), V
IN
= 6V to 26V
∆V
OUT
/V
OUT
Load Regulation,
Note 8
MIC2954-02/-07 (±0.5%), I
L
= 1 to 250mA
MIC2954-03/-08 (±1%), I
L
= 1 to 250mA
V
IN
– V
OUT
Dropout Voltage,
Note 9
I
L
= 1mA
I
L
= 50mA
I
L
= 100mA
I
L
= 250mA
I
GND
Ground Pin Current,
Note 10
I
L
= 1mA
I
L
= 50mA
I
L
= 100mA
I
L
= 250mA
I
GND(DO)
Ground Pin Current at Dropout,
Note 10
V
IN
= 4.5V
300
September 2007
4
M9999-090607
51单片机
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