MIC2940A/2941A
1.2A Low-Dropout Voltage Regulator
General Description
The MIC2940A and MIC2941A are “bulletproof” efficient
voltage regulators with very low dropout voltage (typically
40mV at light loads and 350mV at 1A), and low quiescent
current (240µA typical). The quiescent current of the
MIC2940A increases only slightly in dropout, thus
prolonging battery life. Key MIC2940A features include
protection against reversed battery, fold-back current
limiting, and automotive “load dump” protection (60V
positive transient).
The MIC2940 is available in both
fixed
voltage (3.3V, 5V,
and 12V) and adjustable voltage configurations. The
MIC2940A-xx devices are three pin,
fixed
voltage
regulators. A logic-compatible shutdown input is provided
on the adjustable MIC2941A, which enables the regulator
to be switched on and off.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
•
•
•
•
•
•
•
•
High output voltage accuracy
Guaranteed 1.25A 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
•
Logic-controlled electronic shutdown
•
Output programmable from 1.24V to 26V(MIC2941A)
•
Available in TO-220, TO-263, TO-220-5, and TO-263-5
packages.
Applications
•
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
___________________________________________________________________________________________________________
Pin Configuration
1
2
3
1
2 3
4
5
TO-263-3
(MIC2940A-xxBU/WU)
1
2
3
TO-263-5
(MIC2941ABU/WU)
MIC2941A Pinout
1) Adjust
2) Shutdown
3) Ground
4) Input
5) Output
1 2 3 4
5
TO-220-3
(MIC2940A-xxBT/WT)
MIC2940A Pinout
1) Input
2) Ground
3) Output
TO-220-5
(MIC2941ABT/WT)
The TAB is Ground on TO-220 and TO-263 packages
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2007
M9999-071307
Micrel, Inc.
MIC2940A/2941A
Ordering Information
Part Number
MIC2940A-3.3BT
MIC2940A-3.3BU
MIC2940A-3.3WT
MIC2940A-3.3WU
MIC2940A-5.0BT
MIC2940A-5.0BU
MIC2940A-5.0WT
MIC2940A-5.0WU
MIC2940A-12BT
MIC2940A-12BU
MIC2940A-12WT
MIC2940A-12WU
MIC2941ABT
MIC2941ABU
MIC2941AWT
MIC2941AWU
Note:
1. RoHS compliant with ‘hot-melting solder’ exemption.
Voltage
3.3V
3.3V
3.3V
3.3V
5V
5V
5V
5V
12V
12V
12V
12V
Adj.
Adj.
Adj.
Adj.
Temperature 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
–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
3-Pin TO-220
3-Pin TO-263
3-Pin TO-220
3-Pin TO-263
3-Pin TO-220
3-Pin TO-263
3-Pin TO-220
3-Pin TO-263
3-Pin TO-220
3-Pin TO-263
3-Pin TO-220
3-Pin TO-263
5-Pin TO-220
5-Pin TO-263
5-Pin TO-220
5-Pin TO-263
Lead Finish
Standard
Standard
RoHS Comliant
(1)
RoHS Comliant
(1)
Standard
Standard
RoHS Comliant
(1)
RoHS Comliant
(1)
Standard
Standard
RoHS Comliant
(1)
RoHS Comliant
(1)
Standard
Standard
RoHS Comliant
(1)
RoHS Comliant
(1)
Schematic Diagram
July 2007
2
M9999-071307
Micrel, Inc.
MIC2940A/2941A
Input Supply Voltage ...................................... –20V to +60V
Operating Input Supply Voltage .......................... 2V
†
to 26V
Adjust Input Voltage (Notes
9 and 10)
......... –1.5V to +26V
Shutdown Input Voltage ................................ –0.3V to +30V
Error Comparator Output Voltage ................. –0.3V to +30V
Absolute Maximum Ratings
If Military/Aerospace specified devices are required,
contact your local Micrel representative/distributor for
availability and specifications
Power Dissipation
(Note 1)
.......................Internally Limited
Lead Temperature (soldering, 5 sec.)........................ 260°C
Storage Temperature ................................–65°C to +150°C
Operating Junction Temperature ..............–40°C to +125°C
TO-220 (θ
JC
) ........................................................2°C/W
TO-263 (θ
JC
) ........................................................2°C/W
†
Across the full operating temperature, the minimum input voltage range
for full output current is 4.3V to 26V. Output will remain in-regulation at
lower output voltages and low current loads down to an input of 2V at
25°C.
Electrical Characteristics
Limits in standard typeface are for T
J
= 25°C and limits in
boldface
apply over the full operating temperature range.
Unless otherwise specified, V
IN
= V
OUT
+ 1V, I
L
= 1000mA, C
L
= 10µF. The MIC2941A is programmed to output 5V and
has V
SHUTDOWN
0.6V.
Symbol
V
O
Parameter
Output Voltage Accuracy
5 mA
≤
I
L
≤
1A
∆V
O
∆T
∆V
O
V
O
V
IN
– V
O
Output Voltage Temperature
Coefficient
Line Regulation
Load Regulation
Dropout Voltage (Note 4)
(Note 2)
I
O
= 10mA, (V
OUT
+ 1V)
≤
V
IN
≤
26V
I
L
= 5mA to 1.25A
I
L
= 5mA to 1A (Note
3)
I
L
= 5mA
I
L
= 250mA
I
L
= 1000mA
I
L
= 1250mA
I
GND
Ground Pin Current (Note
5)
I
L
= 5mA
I
L
= 250mA
I
L
= 1000mA
I
L
= 1250mA
I
GNDDO
I
LIMIT
∆V
O
∆P
D
e
n
Ground Pin Current at Dropout
(Note
5)
Current Limit
Thermal Regulation
Output Noise Voltage
(10Hz to 100kHz)
I
L
= 100mA
V
IN
= 0.5V less than designed V
OUT
(V
OUT
3.3)
I
L
= 5mA
V
OUT
= 0V (Note
6)
(Note
7)
C
L
= 10µF
C
L
= 33µF
Condition
Min
–1
–2
–2.5
20
0.06
0.04
60
200
350
400
240
3
22
35
330
1.6
0.05
400
260
Typ
Max
1
2
2.5
100
0.50
0.16
0.20
150
180
250
320
450
600
600
500
4.5
6
35
45
70
600
3.5
0.2
Units
%
%
%
ppm/°C
%
%
%
mV
mV
mV
mV
mV
mV
mV
µA
mA
mA
mA
mA
mA
µA
A
%/W
µV
RMS
µV
RMS
July 2007
3
M9999-071307
Micrel, Inc.
MIC2940A/2941A
Electrical Characteristics (MIC2941A Only)
Parameter
Reference Voltage
(Note
8)
Adjust Pin Bias Current
Reference Voltage Temperature Coefficient
Adjust Pin Bias Current Temperature
Coefficient
Shutdown Input
Input Logic Voltage
Low (ON)
High (OFF)
Shutdown Pin Input Current
V
SHUTDOWN
= 2.4V
V
SHUTDOWN
= 26V
Regulator Output Current in Shutdown
Notes:
1.
Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating
the device outside of its rated operating conditions. The maximum allowable power dissipation is a function of the maximum junction temperature,
T
J(MAX)
, the junction-to-ambient thermal resistance,
θ
JA
, and the ambient temperature, T
A
. The maximum allowable power dissipation at any ambient
temperature is calculated using: P
(MAX)
= (T
J(MAX)
– T
A
) /
θ
JA
. Exceeding the maximum allowable power dissipation will result in excessive die
temperature, and the regulator will go into thermal shutdown.
Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Regulation is measured at constant junction temperature using low duty cycle pulse testing. Changes in output voltage due to heating effects are
covered by the thermal regulation specification.
Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value measured at 1V
differential. At low values of programmed output voltage, the minimum input supply voltage of 4.3V over temperature must be taken into account.
Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin
current.
The MIC2940A features fold-back current limiting. The short circuit (V
OUT
= 0V) current limit is less than the maximum current with normal output
voltage.
Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 200mA load pulse at V
IN
= 20V (a 4W pulse) for T = 10ms.
V
REF
≤
V
OUT
≤
(V
IN
– 1 V), 4.3V
≤
V
IN
26V, 5mA < I
L
≤1.25A,
T
J
≤T
J(MAX)
.
Circuit of Figure 3 with R1
≥
150k
Ω.
V
SHUTDOWN
≥
2 V and V
IN
≤
26 V,V
OUT
= 0.
Condition
Min
1.223
1.210
1.204
Typ
1.235
Max
1.247
1.260
1.266
40
60
Units
V
V
V
nA
nA
ppm/°C
nA/°C
20
20
0.1
1.3
0.7
2.0
30
450
3
50
100
600
750
30
60
V
V
V
µA
µA
µA
µA
µA
µA
(Note
10)
2.
3.
4.
5.
6.
7.
8.
9.
10. When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to ground.
11. Maximum positive supply voltage of 60 V must be of limited duration (< 100 ms) and duty cycle (≤ 1%). The maximum continuous supply voltage is
26V.
July 2007
4
M9999-071307
Micrel, Inc.
MIC2940A/2941A
Typical Characteristics
500
DROPOUT VOLTAGE (mV)
400
300
200
100
0
0.00
Dropout Voltage
vs. Output Current
DROPOUT VOLTAGE (mV)
1000
800
600
400
200
Dropout Voltage
vs. Temperature
OUTPUT VOLTAGE (V)
6
5
4
3
2
1
0
0
Dropout
Characteristics
I
LOAD
= 5mA
I
LOAD
= 1.25A
I
LOAD
= 1.25A
0.25 0.50 0.75 1.00
OUTPUT CURRENT (A)
1.25
0
-60 -30 0 30 60 90 120 150
TEMPERATURE (°C)
1
2
3
4
5
INPUT VOLTAGE (V)
6
40
GROUND CURRENT (mA)
10
Ground Current
vs. Output Current
GROUND CURRENT (µA)
400
Ground Current
vs. Supply Voltage
GROUND CURRENT (mA)
50
40
30
20
10
0
Ground Current
vs. Supply Voltage
300
200
1
100
FIXED 5V
I
LOAD
= 5mA
0
1
2 3 4 5 6 7
SUPPLY VOLTAGE (V)
8
FIXED 3.3V DEVICE
I
LOAD
= 1.25A
0
2
4
6
8
INPUT VOLTAGE (V)
10
0.1
11
0
100
1000
10000
10A
OUTPUT CURRENT (mA)
0
0.40
GROUND CURRENT (mA)
Ground Current
vs. Temperature
GROUND CURRENT (mA)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
Ground Current
vs. Temperature
GROUND CURRENT (mA)
50
40
30
20
10
Ground Current
vs. Temperature
I
LOAD
= 1.25A
0.30
0.20
I
LOAD
= 100mA
0.10
I
LOAD
= 5mA
I
LOAD
= 100mA
0
-60 -30 0 30 60 90 120 150
TEMPERATURE (°C)
0.00
-60 -30 0 30 60 90 120 150
TEMPERATURE (°C)
0.0
-60 -30 0 30 60 90 120 150
TEMPERATURE (°C)
3.40
OUTPUT VOLTAGE (V)
3.38
3.36
Fixed 3.3V Output Voltage
vs. Temperature
2.0
1.8
1.6
CURRENT (A)
1.4
1.2
1.0
0.8
0.6
0.4
0.2
Short Circuit and Maximum
Current vs. Temperature
GROUND CURRENT (µA)
1000
800
600
400
200
0
-200
-30
Ground Current
vs. Input Voltage
R
LOAD
= 100
V
OUT
= V
NOMINAL
– 0.5V
3.34
3.32
3.30
3.28
3.26
3.24
3.22
3.20
-60 -30 0 30 60 90 120 150
TEMPERATURE (°C)
V
OUT
= 0V
FIXED 3.3V
VERSION
3 SAMPLES
0.0
-60 -30 0 30 60 90 120 150
TEMPERATURE (°C)
-20 -10
0
10 20
INPUT VOLTAGE (V)
30
July 2007
5
M9999-071307
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