The MIC39150 and MIC39151 are 1.5A low-dropout linear
voltage regulators that provide a low voltage, high current
output with a minimum of external components. Utilizing
Micrel’s proprietary Super βeta PNP™ pass element, the
MIC39150/1 offers extremely low dropout (typically 375mV at
1.5A) and low ground current (typically 17mA at 1.5A).
The MIC39150/1 is ideal for PC add-in cards that need to
convert from 3.3V to 2.5V or 2.5V to 1.8V. A guaranteed
maximum dropout voltage of 500mV over all operating conditions allows the MIC39150/1 to provide 2.5V from a supply
as low as 3V or 1.8V from a supply as low as 2.3V. The
MIC39150/1 also has fast transient response for heavy
switching applications. This device requires only 10µF of
output capacitance to maintain stability and achieve fast
transient response
The MIC39150/1 is fully protected with overcurrent limiting,
thermal shutdown, reversed-battery protection, reversedlead insertion, and reverse-leakage protection. The MIC39151
offers a TTL-logic compatible enable pin and an error flag that
indicates undervoltage and over current conditions. Offered
in fixed voltages of 2.5V and 1.8V, the MIC39150/1 comes in
the TO-220 and TO-263 packages and is an ideal upgrade to
older, NPN-based linear voltage regulators.
Features
• 1.5A minimum guaranteed output current
• 500mV maximum dropout voltage over temperature
Ideal for 3.0V to 2.5V conversion
Ideal for 2.5 to 1.8V conversion
• 1% initial accuracy
• Low ground current
• Current limiting and Thermal shutdown
• Reversed-battery and reversed lead insertion protection
• Reversed-leakage protection
• Fast transient response
• TO-263 and TO-220 packaging
• TTL/CMOS compatible enable pin (MIC39151 only)
• Error flag output (MIC39151 only)
Applications
• Low-voltage digital ICs
• LDO linear regulator for PC add-in cards
• High-efficiency linear power supplies
• SMPS post regulator
• Low-voltage microcontrollers
• StrongARM™ processor supply
For applications requiring input voltage greater than 16V or
automotive load dump protection, see the MIC29150/1/2/3
family.
Typical Application
MIC39150-2.5
V
INOUT
IN
3.3V
GND
MIC39150
StrongARM is a trademark of Advanced RSIC Machines, Ltd.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
May 20001MIC39150/39151
V
OUT
2.5V
10µF
tantalum
MIC39151
Page 2
MIC39150/39151Micrel
Ordering Information
Part NumberVoltageTemperature RangePackage
MIC39150-1.8BT1.8V–40°C to +125°C3-lead TO-220
MIC39150-1.8BU1.8V–40°C to +125°C3-lead TO-263
MIC39151-1.8BT1.8V–40°C to +125°C5-lead TO-220
MIC39151-1.8BU1.8V–40°C to +125°C5-lead TO-263
MIC39150-2.5BT2.5V–40°C to +125°C3-lead TO-220
MIC39150-2.5BU2.5V–40°C to +125°C3-lead TO-263
MIC39151-2.5BT2.5V–40°C to +125°C5-lead TO-220
MIC39151-2.5BU2.5V–40°C to +125°C5-lead TO-263
Note 1. Exceeding the absolute maximum ratings may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended.
Note 4. P
Note 5. Output voltage temperature coefficient is ∆V
Note 6. V
Note 7. I
Note 8. V
Note 9. For a 2.5V device, V
= (T
D(max)
= VIN – V
DO
voltage is the input-to-output voltage differential with the minimum input voltage being 2.25V. Minimum input operating voltage is 2.25V.
is the quiescent current. IIN = I
GND
≤ 0.8V, VIN ≤ 8V, and V
EN
– TA) ÷θJA, where θJA depends upon the printed circuit layout. See “Applications Information.”
J(max)
OUT
when V
IN
decreases to 98% of its nominal output voltage with VIN = V
OUT
+ I
GND
OUT
OUT
= 0V.
= 2.250V (device is in dropout).
OUT(worst case)
.
÷ (T
J(max)
– T
J(min)
) where T
is +125°C and T
J(max)
+ 1V. For output voltages below 2.25V, dropout
OUT
J(min)
is –40°C.
MIC39150/391514May 2000
Page 5
MIC39150/39151Micrel
0
10
20
30
40
50
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
PSRR (dB)
FREQUENCY (Hz)
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
1.4
1.6
1.822.2
2.4
2.6
2.833.2
3.4
3.6
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
0
5
10
15
20
25
30
35
40
45
50
55
60
65
024681012
GROUND CURRENT (mA)
SUPPLY VOLTAGE (V)
0.30
0.31
0.32
0.33
0.34
0.35
0.36
-40 -20 0 20 40 60 80 100 120
GROUND CURRENT (mA)
TEMPERATURE (°C)
Ground Current
vs. Temperature
I
LOAD
= 10mA
V
OUT
= 2.5V
V
OUT
= 1.8V
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-40 -20 0 20 40 60 80 100 120
SHORT CIRCUIT CURRENT (A)
TEMPERATURE (°C)
Short Circuit vs.
Temperature
typical 1.8V device
typical 2.5V device
Typical Characteristics
Power Supply
60
50
40
30
PSRR (dB)
20
10
Rejection Ratio
VIN = 3.3V
V
= 2.5V
OUT
I
= 1.5A
LOAD
C
= 10µF
OUT
C
= 0
IN
0
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
10
1k
100
FREQUENCY (Hz)
10k
100k
Dropout Voltage
600
500
400
300
200
100
DROPOUT VOLTAGE (mV)
vs. Temperature
V
= 1.8V
OUT
V
= 2.5V
OUT
I
= 1.5A
LOAD
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
1M
Power Supply
Rejection Ratio
VIN = 3.3V
V
= 2.5V
OUT
I
LOAD
C
OUT
C
= 0
IN
1k
10
100
10k
Dropout Characteristics
I
= 100mA
LOAD
I
= 1.5A
LOAD
I
= 750mA
LOAD
= 1.5A
= 47µF
100k
1M
Dropout Voltage
vs. Output Current
500
400
V
OUT
= 1.8V
V
= 2.5V
OUT
300
200
100
DROPOUT VOLTAGE (mV)
0
050010001500
OUTPUT CURRENT (mA)
Ground Current
vs. Output Current
25
20
15
V
= 1.8V
OUT
10
5
GROUND CURRENT (mA)
0
0 250 500 750 10001250 1500
OUTPUT CURRENT (mA)
V
= 2.5V
OUT
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
GROUND CURRENT (mA)
0.2
0.0
May 20005MIC39150/39151
Ground Current
vs. Supply Voltage
I
= 100mA
LOAD
I
= 10mA
LOAD
024681012
SUPPLY VOLTAGE (V)
Ground Current
vs. Temperature
8
7
6
5
V
= 1.8V
4
OUT
3
2
1
GROUND CURRENT (mA)
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
I
LOAD
V
= 2.5V
OUT
= 750mA
Ground Current
vs. Supply Voltage
I
= 1500mA
LOAD
I
= 1000mA
LOAD
I
= 750mA
LOAD
Ground Current
vs. Temperature
25
V
I
LOAD
OUT
= 2.5V
= 1.5A
20
15
V
= 1.8V
OUT
10
5
GROUND CURRENT (mA)
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Page 6
MIC39150/39151Micrel
Error Flag
Pull-Up Resistor
6
5
FLAG HIGH
4
3
2
FLAG VOLTAGE (V)
1
0
0.01 0.1110 100 100010000
(OK)
RESISTANCE (kΩ)
VIN = 5V
FLAG LOW
(FAULT)
Functional Characteristics
Load Transient Response
VIN = 3.3V
= 2.5V
V
OUT
= 10µF
C
OUT
Enable Current
vs. Temperature
12
10
8
6
4
2
ENABLE CURRENT µA)
0
-40 -20 0 20 40 60 80 100120140
VIN = V
OUT
V
= 2.4V
EN
TEMPERATURE (°C)
+ 1V
VIN = 3.3V
= 2.5V
V
OUT
= 47µF
C
OUT
Flag-Low Voltage
250
200
150
100
FLAG VOLTAGE (mV)
vs. Temperature
FLAG-LOW
VOLTAGE
50
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
Load Transient Response
VIN = 2.25V
R
= 22kΩ
PULL-UP
(500mV/div.)
OUTPUT VOL TAGE
(500mA/div.)
LOAD CURRENT
V
(50mV/div.)
OUT
C
OUT
OUTPUT VOL TAGE
I
LOAD
TIME (250µs/div.)
Load Transient Response
= 2.5V
= 10µF
= 10mA
1.5A
100mA
5V
3.3V
(500mV/div.)
OUTPUT VOL TAGE
(500mA/div.)
LOAD CURRENT
1.5A
10mA
TIME (250µs/div.)
(2V/div.)
INPUT VOL TAGE
TIME (500µs/div.)
MIC39150/391516May 2000
Page 7
MIC39150/39151Micrel
Ref.
18V
O.V.
I
LIMIT
Thermal
Shutdown
1.240V1.180V
EN*
IN
FLAG*
GND
OUT
* MIC39151 only
Functional Diagram
May 20007MIC39150/39151
Page 8
MIC39150/39151Micrel
Applications Information
The MIC39150/1 is a high-performance low-dropout voltage
regulator suitable for moderate to high-current voltage regulator applications. Its 500mV dropout voltage at full load and
overtemperature makes it especially valuable in batterypowered systems and as high-efficiency noise filters in postregulator applications. Unlike older NPN-pass transistor designs, where the minimum dropout voltage is limited by the
base-to-emitter voltage drop and collector-to-emitter saturation voltage, dropout performance of the PNP output of these
devices is limited only by the low VCE saturation voltage.
A trade-off for the low dropout voltage is a varying base drive
requirement. Micrel’s Super βeta PNP™ process reduces
this drive requirement to only 2% to 5% of the load current.
The MIC39150/1 regulator is fully protected from damage
due to fault conditions. Current limiting is provided. This
limiting is linear; output current during overload conditions is
constant. Thermal shutdown disables the device when the
die temperature exceeds the maximum safe operating temperature. Transient protection allows device (and load) survival even when the input voltage spikes above and below
nominal. The output structure of these regulators allows
voltages in excess of the desired output voltage to be applied
without reverse current flow.
MIC39150-x.x
V
IN
INOUT
C
IN
GND
Figure 1. Capacitor Requirements
Thermal Design
Linear regulators are simple to use. The most complicated
design parameters to consider are thermal characteristics.
Thermal design requires the following application-specific
parameters:
• Maximum ambient temperature (TA)
• Output Current (I
• Output Voltage (V
OUT
OUT
)
• Input Voltage (VIN)
• Ground Current (I
GND
First, calculate the power dissipation of the regulator from
these numbers and the device parameters from this datasheet.
PD = (VIN – V
OUT) IOUT
+ V
where the ground current is approximated by using numbers
from the “Electrical Characteristics” or “Typical Characteristics.” Then the heat sink thermal resistance is determined
with this formula:
TT
θθθ
=
SA
Where T
J (max)
−
J(max)A
P
D
−+
()
JCCS
≤ 125°C and θCS is between 0° and 2°C/W.
The heat sink may be significantly reduced in applications
where the minimum input voltage is known and is large
)
)
IN IGND
V
OUT
C
OUT
compared with the dropout voltage. Use a series input
resistor to drop excessive voltage and distribute the heat
between this resistor and the regulator. The low dropout
properties of Micrel Super βeta PNP regulators allow significant reductions in regulator power dissipation and the associated heat sink without compromising performance. When
this technique is employed, a capacitor of at least 1µF is
needed directly between the input and regulator ground.
Refer to
Application Note 9
for further details and examples
on thermal design and heat sink specification.
Output Capacitor
The MIC39150/1 requires an output capacitor to maintain
stability and improve transient response. Proper capacitor
selection is important to ensure proper operation. The
MIC39150/1 output capacitor selection is dependent upon
the ESR (equivalent series resistance) of the output capacitor
to maintain stability. When the output capacitor is 10µF or
greater, the output capacitor should have an ESR less than
2Ω. This will improve transient response as well as promote
stability. Ultralow ESR capacitors (<100mΩ), such as ceramic chip capacitors may promote instability. These very low
ESR levels may cause an oscillation and/or underdamped
transient response. A low-ESR solid tantalum capacitor works
extremely well and provides good transient response and
stability over temperature. Aluminum electrolytics can also
be used, as long as the ESR of the capacitor is < 2Ω.
The value of the output capacitor can be increased without
limit. Higher capacitance values help to improve transient
response and ripple rejection and reduce output noise.
Input Capacitor
An input capacitor of 1µF or greater is recommended when
the device is more than 4 inches away from the bulk ac supply
capacitance, or when the supply is a battery. Small, surfacemount, ceramic chip capacitors can be used for the bypassing. The capacitor should be placed within 1" of the device for
optimal performance. Larger values will help to improve
ripple rejection by bypassing the input to the regulator, further
improving the integrity of the output voltage.
Transient Response and 3.3V to 2.5V
or 2.5V to 1.8V Conversion
The MIC39150/1 has excellent transient response to variations in input voltage and load current. The device has been
designed to respond quickly to load current variations and
input voltage variations. Large output capacitors are not
required to obtain this performance. A standard 10µF output
capacitor, preferably tantalum, is all that is required. Larger
values help to improve performance even further.
By virtue of its low-dropout voltage, this device does not
saturate into dropout as readily as similar NPN-based designs. When converting from 3.3V to 2.5V, or 2.5V to 1.8V, the
NPN-based regulators are already operating in dropout, with
typical dropout requirements of 1.2V or greater. To convert
down to 2.5V without operating in dropout, NPN-based
regulators require an input voltage of 3.7V at the very least.
The MIC39150/1 regulator will provide excellent performance
with an input as low as 3.0V or 2.5V, respectively. This gives
MIC39150/391518May 2000
Page 9
MIC39150/39151Micrel
the PNP-based regulators a distinct advantage over older,
NPN-based linear regulators.
Minimum Load Current
The MIC39150 regulator is specified between finite loads. If
the output current is too small, leakage currents dominate
and the output voltage rises. A 10mA minimum load current
is necessary for proper regulation.
Error Flag
The MIC39151 version features an error flag circuit which
monitors the output voltage and signals an error condition
when the voltage 5% below the nominal output voltage. The
error flag is an open-collector output that can sink 10mA
during a fault condition.
Low output voltage can be caused by a number of problems,
including an overcurrent fault (device in current limit) or low
input voltage. The flag is inoperative during overtemperature
shutdown.
Enable Input
The MIC39151 version features an enable input for on/off
control of the device. Its shutdown state draws “zero” current
(only microamperes of leakage). The enable input is TTL/
CMOS compatible for simple logic interface, but can be
connected to up to 20V. When enabled, it draws approximately 15µA.
May 20009MIC39150/39151
Page 10
MIC39150/39151Micrel
Package Information
0.151 D ±0.005
0.108 ±0.005
0.818 ±0.005
(20.78 ±0.13)
(2.74 ±0.13)
0.410 ±0.010
(10.41 ±0.25)
(3.84 D ±0.13)
0.356 ±0.005
(9.04 ±0.13)
0.176 ±0.005
(4.47 ±0.13)
0.590 ±0.005
(14.99 ±0.13)
0.050 ±0.005
(1.27 ±0.13)
7°
0.050 ±0.003
(1.27 ±.08)
0.100 ±0.005
(2.54 ±0.13)
0.108 ±0.005
(2.74 ±0.13)
0.030 ±0.003
(0.76 ±0.08)
3-Lead TO-220 (T)
0.150 D ±0.005
(3.81 D ±0.13)
0.400 ±0.015
(10.16 ±0.38)
0.578 ±0.018
(14.68 ±0.46)
1.140 ±0.010
(28.96 ±0.25)
0.018 ±0.008
(0.46 ±0.020)
0.241 ±0.017
(6.12 ±0.43)
7°
3°
DIMENSIONS:
0.177 ±0.008
(4.50 ±0.20)
0.050 ±0.005
(1.27 ±0.13)
SEATING
PLANE
0.100 ±0.020
(2.54 ±0.51)
INCH
(MM)
7°
Typ.
0.550 ±0.010
(13.97 ±0.25)
0.067 ±0.005
(1.70 ±0.127)
0.268 REF
(6.81 REF)
0.032 ±0.005
(0.81 ±0.13)
0.018 ±0.008
(0.46 ±0.20)
Dimensions:
0.103 ±0.013
(2.62±0.33)
inch
(mm)
5-Lead TO-220-5 (T)
MIC39150/3915110May 2000
Page 11
MIC39150/39151Micrel
0.405±0.005
0.065±0.010
20°±2°
0.100 BSC 0.050
DIM. = INCH
0.405±0.005
0.065±0.010
20°±2°
0.050±0.005
0.360±0.005
0.600±0.025
0.015 ±0.002
3-Lead TO-263 (U)
0.050±0.005
0.360±0.005
0.600±0.025
8° MAX
0.176±0.005
0.050±0.005
SEATING PLANE
+0.004
0.004
–0.008
0.100±0.01
0.176±0.005
0.060±0.005
SEATING PLANE
+0.004
0.004
–0.008
0.067±0.005 0.032 ±0.003
DIM. = INCH
5-Lead TO-263-5 (U)
8° MAX
0.015 ±0.002
0.100±0.01
May 200011MIC39150/39151
Page 12
MIC39150/39151Micrel
MICREL INC. 1849 FORTUNE DRIVESAN JOSE, CA 95131 USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.