MICREL MIC2941ABU, MIC2940A-3.3BT, MIC2940A-3.3BU, MIC2940A-5.0BT, MIC2940A-5.0BU Datasheet
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MIC2940A/2941A Micrel
MIC2940A/2941A
1.25A Low-Dropout Voltage Regulator
Preliminary Information
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 MIC2940Axx devices are three pin fixed voltage regulators. A logiccompatible shutdown input is provided on the adjustable
MIC2941A, which enables the regulator to be switched on and
off.
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 V
• Bar Code Scanners
• Automotive Electronics
• SMPS Post-Regulator/ DC to DC Modules
• Voltage Reference
• High Efficiency Linear Power Supplies
Regulation/Switching
PP
Pin Configuration
12 3
Front View
GROUNDINPUT
TO-220 Package
(MIC2940A-xxBT)
OUTPUT
INPUT GROUND OUTPUT
TO-263 Package
(MIC2940A-xxBU)
12345
TO-263-5 Package
(MIC2941ABU)
MIC2941A Pinout
1) Adjust
2) Shutdown
3) Ground
4) Input
5) Output
12345
TO-220-5 Package
(MIC2941ABT)
The Tab is Ground on TO-220 and TO-263 packages
June 1999 1 MIC2940A/2941A
MIC2940A/2941A Micrel
Absolute Maximum Ratings
If Military/Aerospace specified devices
Ordering Information
Part Number Voltage Temperature Range* Package
MIC2940A-3.3BT 3.3 –40°C to +125°C TO-220
MIC2940A-3.3BU 3.3 –40°C to +125°C TO-263
MIC2940A-5.0BT 5.0 –40°C to +125°C TO-220
MIC2940A-5.0BU 5.0 –40°C to +125°C TO-263
MIC2940A-12BT 12 –40°C to +125°C TO-220
MIC2940A-12BU 12 –40°C to +125°C TO-263
MIC2941ABT Adj –40°C to +125°C TO-220-5
MIC2941ABU Adj –40°C to +125°C TO-263-5
* Junction temperatures
are required, contact your local Micrel
representative/distributor for availability
and specifications.
Power Dissipation (Note 1) ............... Internally Limited
Lead Temperature (Soldering, 5 seconds) ........ 260°C
Storage Temperature Range ............ –65°C to +150°C
Operating Junction Temperature Range
................................................. –40°C to +125°C
TO-220 θJC........................................................ 2 °C/W
TO-263 θJC........................................................ 2 °C/W
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
†
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.
Schematic Diagram
Q6
R1
20 kΩ
Q42
R2
50 kΩ
Q40
Q41
R30
30
kΩ
50 kΩ
10 kΩ
IN
Q15A
Q9
R11
18
kΩ
Q1
10
R5
180
kΩ
R3
50 kΩ
ERROR
C1
20
pF
Q13
R4
13 kΩ
140
Q4Q3
R6
kΩ
Q12
Q38
Q39
Q5
Q2
31.4 kΩ
27.8 kΩ
Q37
R11
20.6
kΩ
R8
R9
R26
60 kΩ
Q7
Q11
Q36
R10
150
Q8
Q20
kΩ
R12
110
kΩ
Q34
R25
2.8 kΩ
Q16
R13
100
Q18
GND
kΩ
Q15B
R22
150 kΩ
Q17
C2
40 pF
R14
350
kΩ
FEEDBACK
R18
20kΩ
Q26
Q25
R17
Q14
12 kΩ
Q22
Q21
R15
100 kΩ
R16
R17
30 kΩ
Q29
Q19
Q31
Q30
DENOTES CONNECTION ON FIXED
VOLTAGE VERSIONS ONLY
Q28
R24
50 kΩ
10 Ω
R21 8 Ω
R23 60 kΩ
Q24
OUT
SENSE
R27
V TAP
R28
Q23
SHDN
MIC2940A/2941A 2 June 1999
MIC2940A/2941A Micrel
Electrical Characteristics
Limits in standard typeface are for TJ = 25°C and limits in boldface apply over the full operating temperature range.
Unless otherwise specified, VIN = V
V
SHUTDOWN
≤ 0.6V.
Symbol Parameter Conditions Min Typical Max Units
V
O
Output Voltage –1 1 %
Accuracy –2 2
∆V
O
Output Voltage (Note 2) 20 100 ppm/°C
∆T Temperature Coef.
∆V
O
V
O
∆V
O
V
O
VIN – V
O
Line Regulation VIN = V
Load Regulation IL = 5mA to 1.25A 0.04 0.16 %
Dropout Voltage IL = 5mA 60 150 mV
(Note 4) 180
+ 1V, IL = 1000mA, CL = 10µF. The MIC2941A is programmed to output 5V and has
OUT
5 mA ≤ IL ≤ 1A –2.5 2.5
+ 1V to 26V 0.03 0.10 %
OUT
0.40
IL = 5mA to 1A 0.20 %
(Note 3)
IL = 250mA 200 250
320
IL = 1000mA 350 450
600
IL = 1250mA 400 600
I
GND
I
GNDDO
I
LIMIT
∆V
∆P
e
n
Ground Pin Current IL = 5mA 240 350 µA
(Note 5) 500
IL = 250mA 3 4.5 mA
6
IL = 1000mA 22 35
45
IL = 1250mA 35 70
Ground Pin VIN = 0.5V less than designed V
Current at Dropout (V
≥ 3.3V)
OUT
OUT
330 600 µA
(Note 5) IL = 5mA
Current Limit V
= 0V 1.6 2.4 A
OUT
(Note 6) 3
O
D
Thermal Regulation (Note 7) 0.05 0.2 %/W
Output Noise CL = 10µF 400 µV RMS
Voltage
(10Hz to 100kHz) CL = 33µF 260
IL = 100mA
June 1999 3 MIC2940A/2941A
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