MIC49150
1.5A Low Voltage LDO Regulator
w/Dual Input Voltages
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
November 2006
1 M9999-111306
General Description
The MIC49150 is a high-bandwidth, low-dropout, 1.5A volt-
age regulator ideal for powering core voltages of low-
power microprocessors. The MIC49150 implements a dual
supply configuration allowing for very low output
impedance and very fast transient response.
The MIC49150 requires a bias input supply and a main
input supply, allowing for ultra-low input voltages on the
main supply rail. The input supply operates from 1.4V to
6.5V and the bias supply requires between 3V and 6.5V
for proper operation. The MIC49150 offers fixed output
voltages from 0.9V to 1.8V and adjustable output voltages
down to 0.9V.
The MIC49150 requires a minimum of output capacitance
for stability, working optimally with small ceramic
capacitors.
The MIC49150 is available in an 8-pin power MSOP pack-
age and a 5-pin S-Pak. Its operating temperature range is
–40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• Input Voltage Range:
– V
IN
: 1.4V to 6.5V
– V
BIAS
: 3.0V to 6.5V
• Stable with 1µF ceramic capacitor
• ±1% initial tolerance
• Maximum dropout voltage (V
IN
–V
OUT
) of 500mV
over temperature
• Adjustable output voltage down to 0.9V
• Ultra fast transient response (Up to 10MHz bandwidth)
• Excellent line and load regulation specifications
• Logic controlled shutdown option
• Thermal shutdown and current limit protection
• Power MSOP-8 and S-Pak packages
• Junction temperature range: –40°C to 125°C
Applications
• Graphics processors
• PC add-in cards
• Microprocessor core voltage supply
• Low voltage digital ICs
• High efficiency linear power supplies
• SMPS post regulators
Typical Application
MIC49150B
R
GND
C
OUT
= 1µF
Ceramic
BIAS
IN OUT
C
BIAS
= 1µF
Ceramic
V
OUT
= 1.0VV
IN
= 1.8V
V
BIAS
= 3.3V ADJ
C
IN
= 1µF
Ceramic
R1
R2
Low Voltage,
Fast Transient Response Regulator
Micrel, Inc. MIC49150
November 2006
2
M9999-111306
Ordering Information
Part Number
Standard Pb-Free /
RoHS Compliant
Output
Current Voltage Junction
Temp. Range Package
MIC49150-0.9BMM MIC49150-0.9YMM 1.5A 0.9V –40° to +125°C 8-Pin Power MSOP
MIC49150-1.2BMM MIC49150-1.2YMM 1.5A 1.2V –40° to +125°C 8-Pin Power MSOP
MIC49150-1.5BMM MIC49150-1.5YMM 1.5A 1.5V –40° to +125°C 8-Pin Power MSOP
MIC49150-1.8BMM MIC49150-1.8YMM 1.5A 1.8V –40° to +125°C 8-Pin Power MSOP
MIC49150BMM MIC49150YMM 1.5A Adj. –40° to +125°C 8-Pin Power MSOP
MIC49150-0.9BR MIC49150-0.9WR* 1.5A 0.9V –40° to +125°C 5-Pin S-PAK
MIC49150-1.2BR MIC49150-1.2WR* 1.5A 1.2V –40° to +125°C 5-Pin S-PAK
MIC49150-1.5BR MIC49150-1.5WR* 1.5A 1.5V –40° to +125°C 5-Pin S-PAK
MIC49150-1.8BR MIC49150-1.8WR* 1.5A 1.8V –40° to +125°C 5-Pin S-PAK
MIC49150BR MIC49150WR* 1.5A Adj. –40° to +125°C 5-Pin S-PAK
* RoHS Compliant with ‘high-melting solder’ exemption.
Pin Configuration
1
2
3
4
8
7
6
5
GND
GND
GND
GND
EN/ADJ.
VBIAS
VIN
VOUT
TAB
5VOUT
4
VBIAS
3
2
VIN
1 EN/ADJ
.
GND
8-Pin Power MSPO (MM) 5-Pin S-Pak (R)
Pin Description
Pin Number
8-MSOP
Pin Number
5-SPak
Pin Name Pin Name
EN Enable (Input): CMOS compatible input. Logic high = enable,
logic low = shutdown.
1 1
ADJ Adjustable regulator feedback input. Connect to resistor
voltage divider.
2 2 VBIAS
Input Bias Voltage for powering all circuitry on the regulator
with the exception of the output power device.
3 4 VIN
Input voltage which supplies current to the output power
device.
4 5 OUT Regulator Output.
5/6/7/8 3 GND Ground (TAB is connected to ground on S-Pak).
Micrel, Inc. MIC49150
November 2006
3
M9999-111306
Absolute Maximum Ratings(1)
Supply Voltage (V
IN
).........................................................8V
Bias Supply Voltage (V
BIAS
)..............................................8V
Enable Input Voltage (V
EN
)...............................................8V
Power Dissipation .....................................Internally Limited
ESD Rating
(3)
.................................................................. 4kV
Operating Ratings(2)
Supply Voltage (V
IN
)......................................... 1.4V to 6.5V
Bias Supply Voltage (V
BIAS
)................................. 3V to 6.5V
Enable Input Voltage (V
EN
).................................. 0V to 6.5V
Junction Temperature (T
J
) ..................–40°C T
J
+125°C
Package Thermal Resistance
MSOP-8 (θ
JA
).....................................................80°C/W
S-Pak (θ
JC
) ..........................................................2°C/W
Electrical Characteristics(4)
T
A
= 25°C with V
BIAS
= V
OUT
+ 2.1V; V
IN
= V
OUT
+ 1V; bold values indicate –40°C< T
J
< +125°C, unless noted
(5)
.
Parameter Condition Min Typ Max Units
Output Voltage Accuracy At 25°C
Over temperature range
–1
–2
+1
+2
%
%
Line Regulation V
IN
= V
OUT
+1V to 6.5V –0.1 0.01 +0.1 %/V
Load Regulation I
L
= 0mA to 1.5A 0.2 1
1.5
%
%
Dropout Voltage (V
IN
- V
OUT
) I
L
= 750mA
I
L
= 1.5A
130
280
200
300
400
500
mV
mV
mV
mV
Dropout Voltage (V
BIAS
- V
OUT
),
Note 5
I
L
= 750mA
I
L
= 1.5A
1.3
1.65
1.9
2.1
V
V
V
Ground Pin Current, Note 6 I
L
= 0mA
I
L
= 1.5A
15
15
25
30
mA
mA
mA
Ground Pin Current in
Shutdown
V
EN
0.6V, (I
BIAS
+ I
CC
), Note 7 0.5
1
2
µA
µA
Current thru V
BIAS
I
L
= 0mA
I
L
= 1.5A
9
32
15
25
mA
mA
mA
Current Limit MIC49150 1.6 2.3 3.4
4
A
A
Enable Input (Note 7)
Enable Input Threshold
(Fixed Voltage only)
Regulator enable
Regulator shutdown
1.6
0.6
V
V
Enable Pin Input Current Independent of state 0.1 1 µA
Reference
Reference Voltage 0.891
0.882
0.9 0.909
0.918
V
V
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
5. For V
OUT
1V, V
BIAS
dropout specification does not apply due to a minimum 3V V
BIAS
input.
6. I
GND
= I
BIAS
+ (I
IN
– I
OUT
). At high loads, input current on V
IN
will be less than the output current, due to drive current being supplied by V
BIAS
.
7. Fixed output voltage versions only.
Micrel, Inc. MIC49150
November 2006
4
M9999-111306
Typical Characteristics
0
10
20
30
40
50
60
70
80
0.01 0.1 1 10 100 1000
PSRR (dB)
FREQUENCY (kHz)
Power Supply Re
j
ection Ratio
(Input Suppl )
V
BIAS
=3.3V
V
IN
=1.8V
V
OUT
=1.0V
I
OUT
=1.5A
C
OUT
=1µFceramic
0
10
20
30
40
50
60
70
80
0.01 0.1 1 10 100 1000
PSRR (dB)
FREQUENCY (kHz)
Power Supply Re
j
ection Ratio
(Bias Suppl )
V
BIAS
=3.3V
V
IN
=1.8V
V
OUT
=1.0V
I
OUT
=1.5A
C
OUT
=1µFceramic
0
50
100
150
200
250
300
0
200
400
600
800
1000
1200
1400
1600
DROPOUT VOLTAGE (mV)
OUTPUT CURRENT (mA)
Dropout
V
oltage
(Input Suppl )
V
BIAS
=5V
V
OUT
=1.0V
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0
200
400
600
800
1000
1200
1400
1600
DROPOUT VOLTAGE (V)
OUTPUT CURRENT (mA)
Dropout
V
oltage
(Bias Supply)
V
IN
=2.5V
V
OUT
=1.5V
0
50
100
150
200
250
300
350
400
-40 -20 0 20 40 60 80 100 120
DROPOUT VOLTAGE (mV)
TEMPERATURE(°C)
Dropout
V
oltage
vs. Temperature
(Input Supply)
V
BIAS
=5V
I
OUT
=1.5A
V
OUT
=1.5V
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-40 -20 0 20 40 60 80 100 120
DROPOUT VOLTAGE (V)
TEMPERATURE(°C)
Dropout
V
oltage
vs. Temperature
(Bias Supply)
V
IN
=2.5V
I
OUT
=1.5A
V
OUT
=1.5V
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 0.5 1 1.5 2 2.5
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Dropout Characteristics
(Input Voltage)
V
BIAS
=5V
V
OUT
=1.5V
I
OUT
=10mA
I
OUT
=1.5A
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
01234567
OUTPUT VOLTAGE (V)
BIAS VOLTAGE (V)
Dropout Characteristics
(Bias Voltage)
V
IN
=2.5V
V
OUT
=1.5V
I
OUT
=10mA
I
OUT
=1.5A
1.495
1.496
1.497
1.498
1.499
1.500
1.501
1.502
1.503
1.504
1.505
0
200
400
600
800
1000
1200
1400
1600
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
Load Regulation
V
BIAS
=5V
V
IN
=2.5V
0
50
100
150
200
250
300
3 3.5 4 4.5 5 5.5 6 6.5
BIAS CURRENT (mA)
BIAS VOLTAGE (V)
Maximum Bias Current
vs. Bias Voltage
V
ADJ
=0V
I
OUT
=1.5A
V
IN
=2.5V
*Note: Maximum bias current is bias
current with input in dropout
0
50
100
150
200
250
300
-40 -20 0 20 40 60 80 100 120
BIAS CURRENT (mA)
TEMPERATURE(°C)
Maximum Bias Current
vs. Temperature
V
BIAS
=5V
V
ADJ
=0V
V
IN
=2.5V
0
5
10
15
20
25
30
35
40
45
-40 -20 0 20 40 60 80 100 120
BIAS CURRENT (mA)
TEMPERATURE (°C)
Bias Current
vs. Temperature
V
IN
=2.5V
V
OUT
=1.5V
V
BIAS
=5V
I
OUT
=10mA
I
OUT
= 1500mA
I
OUT
= 100mA
I
OUT
= 750mA
Micrel, Inc. MIC49150
November 2006
5
M9999-111306
Typical Characteristics (cont.)
0
10
20
30
40
50
0
200
400
600
800
1000
1200
1400
1600
CURRENT (mA)
OUTPUT CURRENT (mA)
Bias Current
vs. Output Current
V
BIAS
=5V
V
IN
=2.5V
V
OUT
=1.5V
I
BIAS
0
2
4
6
8
10
12
14
3 3.5 4 4.5 5 5.5 6 6.5
GROUND CURRENT (mA)
BIAS VOLTAGE (V)
Ground Current
vs. Bias Voltage
I
OUT
=0mA
V
IN
=2.5V
V
OUT
=1.5V
0
2
4
6
8
10
12
14
3 3.5 4 4.5 5 5.5 6 6.5
GROUND CURRENT (mA)
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
= 100mA
V
IN
=2.5V
V
OUT
=1.5V
I
BIAS
0
10
20
30
40
50
3 3.5 4 4.5 5 5.5 6 6.5
GROUND CURRENT (mA)
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
= 750mA
V
IN
=2.5V
V
OUT
=1.5V
I
BIAS
0
10
20
30
40
50
3 3.5 4 4.5 5 5.5 6 6.5
GROUND CURRENT (mA)
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
= 1500mA
V
IN
=2.5V
V
OUT
=1.5V
I
BIAS
0
2
4
6
8
10
12
14
16
18
20
0 0.5 1 1.5 2 2.5
BIAS CURRENT (mA)
INPUT VOLTAGE (V)
Bias Current
vs. Input Voltage
V
BIAS
=5V
V
OUT
=1.5V
I
OUT
= 100mA
I
OUT
=0mA
0
50
100
150
200
250
300
0 0.5 1 1.5 2 2.5
BIAS CURRENT (mA)
INPUT VOLTAGE (V)
Bias Current
vs. Input Voltage
V
BIAS
=5V
V
OUT
=1.5V 1500mA
750mA
0.899
0.900
0.901
1.4 2.4 3.4 4.4 5.4 6.4
REFERENCE VOLTAGE (V)
INPUT VOLTAGE (V)
Reference
V
oltage
vs. Input Voltage
V
BIAS
=5V
0.899
0.900
0.901
3 3.5 4 4.5 5 5.5 6 6.5
REFERENCE VOLTAGE (V)
BIAS VOLTAGE (V)
Reference
V
oltage
vs. Bias Voltage
V
IN
=2.5V
1.45
1.46
1.47
1.48
1.49
1.50
1.51
1.52
1.53
1.54
1.55
-40 -20 0 20 40 60 80 100 120
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
Output
V
oltage
vs. Temperature
V
BIAS
=5V
V
IN
=2.5V
0
0.5
1.0
1.5
2.0
2.5
3.0
-40 -20 0 20 40 60 80 100 120
SHORT CIRCUIT CURRENT (A)
TEMPERATURE (°C)
Short Circuit Current
vs. Temperature
V
BIAS
=5V
V
IN
=2.5V
V
OUT
=0V
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
3 3.5 4 4.5 5 5.5 6 6.5
ENABLE THRESHOLD (V)
BIAS VOLTAGE (V)
Enable Threshold
vs. Bias Voltage
V
IN
=2.5V
ON
OFF
Micrel, Inc. MIC49150
November 2006
6
M9999-111306
Typical Characteristics (cont.)
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
-40 -20 0 20 40 60 80 100 120
ENABLE THRESHOLD (V)
TEMPERATURE (°C)
Enable Threshold
vs. Temperature
V
BIAS
=5V
V
IN
=2.5V
ON
OFF
Micrel, Inc. MIC49150
November 2006
7
M9999-111306
Functional Characteristics
Micrel, Inc. MIC49150
November 2006
8
M9999-111306
Functional Diagram
V
OUT
Enable Bandgap
V
BIAS
V
IN
Ilimit
V
IN
Open
Circuit R1
R2
Fixed
Adj.
Fixed
V
EN
/
ADJ
Micrel, Inc. MIC49150
November 2006
9
M9999-111306
Application Information
The MIC49150 is an ultra-high performance, low-dropout
linear regulator designed for high current applications
requiring fast transient response. The MIC49150 utilizes
two input supplies, significantly reducing dropout
voltage, perfect for low-voltage, DC-to-DC conversion.
The MIC49150 requires a minimum of external comp-
onents and obtains a bandwidth of up to 10MHz. As a
µCap regulator, the output is tolerant of virtually any type
of capacitor including ceramic type and tantalum type
capacitors.
The MIC49150 regulator is fully protected from damage
due to fault conditions, offering linear current limiting and
thermal shutdown.
Bias Supply Voltage
V
BIAS
, requiring relatively light current, provides power to
the control portion of the MIC49150. V
BIAS
requires
approximately 33mA for a 1.5A load current. Dropout
conditions require higher currents. Most of the biasing
current is used to supply the base current to the pass
transistor. This allows the pass element to be driven into
saturation, reducing the dropout to 300mV at a 1.5A load
current. Bypassing on the bias pin is recommended to
improve performance of the regulator during line and
load transients. Small ceramic capacitors from V
BIAS
to
ground help reduce high frequency noise from being
injected into the control circuitry from the bias rail and
are good design practice. Good bypass techniques
typically include one larger capacitor such as 1µF
ceramic and smaller valued capacitors such as 0.01µF
or 0.001µF in parallel with that larger capacitor to
decouple the bias supply. The V
BIAS
input voltage must
be 1.6V above the output voltage with a minimum V
BIAS
input voltage of 3 volts.
Input Supply Voltage
VIN provides the high current to the collector of the pass
transistor. The minimum input voltage is 1.4V, allowing
con-version from low voltage supplies.
Output Capacitor
The MIC49150 requires a minimum of output capaci-
tance to maintain stability. However, proper capacitor
selection is important to ensure desired transient
response. The MIC49150 is specifically designed to be
stable with virtually any capacitance value and ESR. A
1µF ceramic chip capacitor should satisfy most app-
lications. Output capacitance can be increased without
bound. See “Typical Characteristic” for examples of load
transient response.
X7R dielectric ceramic capacitors are recommended
because of their temperature performance. X7R-type
capacitors change capacitance by 15% over their
operating temperature range and are the most stable
type of ceramic capacitors. Z5U and Y5V dielectric
capacitors change value by as much as 50% and 60%
respectively over their operating temperature ranges. To
use a ceramic chip capacitor with Y5V dielectric, the
value must be much higher than an X7R ceramic or a
tantalum capacitor to ensure the same capacitance
value over the operating temperature range. Tantalum
capacitors have a very stable dielectric (10% over their
operating temperature range) and can also be used with
this device.
Input Capacitor
An input capacitor of 1µF or greater is recommended
when the device is more than 4" away from the bulk
supply capacitance, or when the supply is a battery.
Small, surface-mount, 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.
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 (T
A
)
• Output current (I
OUT
)
• Output voltage (V
OUT
)
• Input voltage (V
IN
)
• Ground current (I
GND
)
First, calculate the power dissipation of the regulator
from these numbers and the device parameters from this
datasheet.
P
D
= V
IN
× I
IN
+ V
BIAS
× I
BIAS
– V
OUT
× I
OUT
The input current will be less than the output current at
high output currents as the load increases. The bias
current is a sum of base drive and ground current.
Ground current is constant over load current. Then the
heat sink thermal resistance is determined with this
formula:
()
CSJC
D
AJ(MAX)
SA
P
TT
+−
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−
=
The heat sink may be significantly reduced in
applications where the maximum input voltage is known
and large 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 the MIC49150
allow significant reductions in regulator power dissipation
and the associated heat sink without compromising
performance. When this technique is employed, a
Micrel, Inc. MIC49150
November 2006
10 M9999-111306
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.
Minimum Load Current
The MIC49150, unlike most other high current
regulators, does not require a minimum load to maintain
output voltage regulation.
Power MSOP-8 Thermal Characteristics
One of the secrets of the MIC49150’s performance is its
power MSOP-8 package featuring half the thermal
resistance of a standard MSOP-8 package. Lower
thermal resistance means more output current or higher
input voltage for a given package size.
Lower thermal resistance is achieved by joining the four
ground leads with the die attach paddle to create a
single-piece electrical and thermal conductor. This
concept has been used by MOSFET manufacturers for
years, proving very reliable and cost effective for the
user.
Thermal resistance consists of two main elements,
JC
(junction-to-case thermal resistance) and
CA
(case-to-
ambient thermal resistance). See Figure 1.
JC
is the
resistance from the die to the leads of the package.
CA
is the resistance from the leads to the ambient air and it
includes
CS
(case-to-sink thermal resistance) and
SA
(sink-to-ambient thermal resistance).
Using the power MSOP-8 reduces the
JC
dramatically
and allows the user to reduce
CA
. The total thermal
resistance,
JA
(junction-to-ambient thermal resistance)
is the limiting factor in calculating the maximum power
dissipation capability of the device. Typically, the power
MSOP-8 has a
JA
of 80°C/W, this is significantly lower
than the standard MSOP-8 which is typically 160°C/W.
CA
is reduced because pins 5 through 8 can now be
soldered directly to a ground plane which significantly
reduces the case-to-sink thermal resistance and sink to
ambient thermal resistance.
Low-dropout linear regulators from Micrel are rated to a
maximum junction temperature of 125°C. It is important
not to exceed this maximum junction temperature during
operation of the device. To prevent this maximum
junction temperature from being exceeded, the
appropriate ground plane heat sink must be used.
q
JA
q
JC
q
CA
printed circuit board
ground plane
heat sink area
MSOP-8
AMBIENT
Figure 1. Thermal Resistance
Figure 2 shows copper area versus power dissipation
with each trace corresponding to a different temperature
rise above ambient.
From these curves, the minimum area of copper
necessary for the part to operate safely can be
determined. The maximum allowable temperature rise
must be calculated to determine operation along which
curve.
0
100
200
300
400
500
600
700
800
900
0 0.25 0.50 0.75 1.00 1.25 1.50
COPPER AREA (mm
2
)
POWER DISSIPATION (W)
Figure 2. Copper Area vs. Power-MSOP
Power Dissipation (∆T
JA
)
0
100
200
300
400
500
600
700
800
900
0 0.25 0.50 0.75 1.00 1.25 1.50
COPPER AREA (mm
2
)
POWER DISSIPATION (W)
85°C 50°C 25°C
TJ=125°C
Figure 3. Copper Area vs. Power-MSOP
Power Dissipation (T
A
)
Micrel, Inc. MIC49150
November 2006
11 M9999-111306
T = T
J(max)
– T
A(max)
T
J(max)
= 125°C
T
A(max)
= maximum ambient operating temp-
erature
For example, the maximum ambient temperature is
50°C, the T is determined as follows:
T = 125°C – 50°C
T = 75°C
Using Figure 2, the minimum amount of required copper
can be determined based on the required power
dissipation. Power dissipation in a linear regulator is
calculated as follows:
P
D
= V
IN
× I
IN
+ V
BIAS
× I
BIAS
– V
OUT
× I
OUT
Using a typical application of 750mA output current, 1.2V
output voltage, 1.8V input voltage and 3.3V bias voltage,
the power dissipation is as follows:
P
D
= (1.8V) × (730mA) + 3.3V(30mA) – 1.2V(750mA)
At full current, a small percentage of the output current is
supplied from the bias supply, therefore the input current
is less than the output current.
P
D
= 513mW
From Figure 2, the minimum current of copper required
to operate this application at a T of 75°C is less than
100mm
2
.
Quick Method
Determine the power dissipation requirements for the
design along with the maximum ambient temperature at
which the device will be operated. Refer to Figure 3,
which shows safe operating curves for three different
ambient temperatures: 25°C, 50°C and 85°C. From
these curves, the minimum amount of copper can be
determined by knowing the maxi-mum power dissipation
required. If the maximum ambient temperature is 50°C
and the power dissipation is as above, 513mW, the
curve in Figure 3 shows that the required area of copper
is less than 100mm
2
.
The
JA
of this package is ideally 80°C/W, but it will vary
depending upon the availability of copper ground plane
to which it is attached.
Adjustable Regulator Design
The MIC49150 adjustable version allows programming
the output voltage anywhere between 0.9Vand 5V. Two
resistors are used. The resistor value between V
OUT
and
the adjust pin should not exceed 10k. Larger values
can cause instability. The resistor values are calculated
by:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−×= 1
0.9
V
R2R1
OUT
Where V
OUT
is the desired output voltage.
Enable
The fixed output voltage versions of the MIC49150
feature an active high enable input (EN) that allows on-
off control of the regulator. Current drain reduces to
“zero” when the device is shutdown, with only
microamperes of leakage current. The EN input has
TTL/CMOS compatible thresholds for simple logic
interfacing. EN may be directly tied to V
IN
and pulled up
to the maximum supply voltage.
Micrel, Inc. MIC49150
November 2006
12 M9999-111306
Package Information
8-Pin MSOP (MM)
5-Pin S-Pak (R)
Micrel, Inc. MIC49150
November 2006
13 M9999-111306
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
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indemnify Micrel for any damages resulting from such use or sale.
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