MIC23201
2MHz PWM 2A Buck Regulator with
Hyper Speed Control™
General Description
Features
The MIC23201 is a high efficiency 2MHz 2A synchronous
buck regulator with Hyper Speed Control. Micrel’s Hyper
Speed Control provides ultra-fast transient response which
is perfectly suited for supplying processor core voltages.
An additional benefit of this proprietary architecture is very
low output ripple voltage throughout the entire load range
with the use of small output capacitors. The tiny 3mm x
3mm MLF® package saves precious board space and
requires only three external components.
The MIC23201 is designed for use with a very small
inductor, down to 1µH, and an output capacitor as small as
22µF that enables a total solution size, less than 1.5mm
height.
The MIC23201 provides a constant switching frequency
around 2MHz while achieving peak efficiencies up to 90%.
The MIC23201 is available in 10-pin 3mm x 3mm MLF
package with an operating junction temperature range
from –40C to +125C.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Input voltage: 2.7V to 5.5V
2A output current
Up to 90% peak efficiency
Programmable Soft-Start
Power Good Indicator
2MHz switching frequency
Safe for pre-biased output
Ultra fast transient response
Low voltage output ripple, 16mV at full load
Fully integrated MOSFET switches
0.01µA shutdown current
Thermal shutdown and current limit protection
Output Voltage as low as 0.95V
10-pin 3mm x 3mm MLF
–40C to +125C operating junction temperature range
Applications
Low Voltage Point of Load
Blu Ray DVD Players
Networking Equipment
Set Top Boxes
____________________________________________________________________________________________________________
Typical Application
Efficiency (VIN = 3.3V)
vs. Output Current
100
90
EFFICIENCY (%)
80
2.5V
1.8V
1.5V
1.2V
0.95V
70
60
50
40
30
20
10
VIN = 3.3V
0
0
0.6
1.2
1.8
2.4
3
OUTPUT CURRENT (A)
Hyper Speed Control is a trademark of Micrel, Inc.
MLF and MicroLeadFrame are registered trademark Amkor Technology Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
August 2012
M9999-082912-A
Micrel Inc.
MIC23201
Ordering Information
Part Number
Marking
Code
Nominal Output
Voltage
MIC23201YML
201A
ADJ
Package
10-pin 3mm x 3mm MLF
Junction
Temp. Range
-40C to +125C
Lead
Finish
Pb-Free
Notes:
1. Other options available. Contact Micrel for details.
2.
MLF is GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Pin Configuration
10 Pin 3mm x 3mm MLF (ML)
(Top View)
Pin Description
Pin Number
Pin Name
1
SW
Switch output: Internal power MOSFET output switches.
2
EN
Enable input: Logic high enables operation of the regulator. Logic low will shut down the device. Do
not leave floating.
3
SNS
Sense input: Connect to VOUT as close to output capacitor as possible to sense output voltage.
4
FB
Feedback input: The FB pin is regulated to 0.62V. Connect a resistor divider from the output to
ground to set the output voltage.
5
PG
Power Good output: Open Drain output for the power good indicator. Place a resistor between this
pin and a voltage source to detect a power good condition.
6
SS
Soft Start: Place a capacitor from SS pin to ground to program the soft start time. Do not leave this
pin floating. Minimum of 100pF CSS is required.
7
AGND
Analog Ground: Connect to central ground point where all high current paths meet (CIN, COUT,
PGND) for best operation.
8
SVIN
Signal input voltage: This pin is connected externally to the VIN pin. A 2.2µF ceramic capacitor from
the SVIN pin to AGND must be placed next to the IC.
9
VIN
10
PGND
Power Ground.
EP
ePad
Thermal pad. It must be connected to PGND on the PCB to improve the thermal performance.
August 2012
Pin Function
Power supply input voltage: The VIN pin is the input supply to the internal P-Channel Power
MOSFET. A 22µF ceramic is recommended for bypassing at VIN pin.
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M9999-082912-A
Micrel Inc.
MIC23201
Absolute Maximum Ratings (1)
Operating Ratings (2)
Supply Voltage (VIN, SVIN)……………………………... ..6V
Sense (VSNS).. ..................................................................6V
Power Good (PG)……................................................. ....6V
Output Switch Voltage ……………………………..…….6V
Enable Input Voltage (VEN)............................... -0.3V to VIN
Storage Temperature Range………………-65C to +150C
ESD Rating(3) ……………………………………………….1kV
Supply Voltage (VIN) ... …………………………..2.7V to 5.5V
Enable Input Voltage (VEN) .. ……………………….0V to VIN
Output Voltage Range (VSNS) ………………….0.95V to 3.6V
Junction Temperature Range (TJ) .... ….-40C TJ +125C
Thermal Resistance
3mm x 3mm MLF-10 (JA) .............................60.7C/W
3mm x 3mm MLF-10 (JC) .............................28.7C/W
Electrical Characteristics (4)
TA = 25°C; VIN = VEN = 3.3V; L = 1.0µH; COUT = 22µF unless otherwise specified. Bold values indicate –40°C ≤ TJ ≤
+125°C, unless noted.
Parameter
Condition
Min
Supply Voltage Range
Under-Voltage Lockout Threshold
Typ
2.7
VIN Rising
2.45
Under-Voltage Lockout Hysteresis
2.55
Max
Units
5.5
V
2.65
V
200
mV
Quiescent Current
IOUT = 0mA , SNS > 1.2 * VOUT Nominal
1.15
3.35
mA
Shutdown Current
VEN = 0V; VIN = 5.5V
1.34
5
µA
Feedback Voltage
ILOAD = 20mA
0.62
0.635
V
0.604
Feedback Bias Current
Current Limit
Output Voltage Line Regulation
Output Voltage Load Regulation
PWM Switch ON-Resistance
SNS = 0.9*VOUTNOM
2.3
1
µA
4.4
A
0.3
%/V
0.46
%
0.71
%
VIN = 3.6V to 5.5V if VOUTNOM < 2.5V, ILOAD = 20mA
VIN = 4.5V to 5.5V if VOUTNOM ≥ 2.5V, ILOAD = 20mA
20mA < ILOAD < 500mA, VIN = 3.6V if VOUTNOM < 2.5V
20mA < ILOAD < 500mA, VIN = 5.0V if VOUTNOM ≥ 2.5V
20mA < ILOAD < 1A, VIN = 3.6V if VOUTNOM < 2.5V
20mA < ILOAD < 1A, VIN = 5.0V if VOUTNOM ≥ 2.5V
ISW = 100mA PMOS
0.200
ISW = -100mA NMOS
0.190
Switching Frequency
IOUT = 120mA
2
MHz
Maximum Duty Cycle
VFB = 0V
Soft Start Time
VOUT = 90%, CSS=470pF
300
µs
Soft Start Current
VSS = 0V
2.7
µA
Power Good Threshold (Rising)
% of VNOMINAL
80
85
%
90
95
%
Power Good Hysteresis
7
%
Power Good Delay
68
µs
85
Ω
Power Good Pull Down Resistance
IPG = 250µA
Enable Threshold
Turn-On
0.5
Enable Input Current
Over Temperature Shutdown
TJ Rising
Over Temperature Shutdown
Hysteresis
0.9
1.2
V
0.1
2
µA
160
C
20
C
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, 1.5kΩ in series with 100pF.
4. Specification for packaged product only.
August 2012
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M9999-082912-A
Micrel Inc.
MIC23201
Typical Characteristics
30
20
VOUT = 1.8V
IOUT = 0A
SWITCHING
0
0.640
7.0
FEEDBACK VOLTAGE (V)
40
10
6.0
5.0
4.0
3.0
2.0
1.0
3.0
3.5
4.0
4.5
5.0
3.0
INPUT VOLTAGE (V)
4.0
4.5
5.0
5.5
2.5
1.0%
0.8%
0.6%
0.4%
8
6
4
2
VOUT = 1.8V
IOUT = 0A to 2A
0
4.5
5.0
5.5
3.0
3.5
4.0
4.5
2200
2000
1800
1600
VOUT = 1.8V
IOUT = 0A
4.0
4.5
INPUT VOLTAGE (V)
August 2012
5.0
5.0
5.5
Falling
0.40
0.20
2.5
3.0
5.5
3.5
4.0
4.5
INPUT VOLTAGE (V)
Power Good Threshold/VREF
Ratio vs. Input Voltage
100
1.25
1.00
0.75
0.50
0.25
2.5
3.0
3.5
4.0
4.5
5.0
90
80
70
60
50
40
30
20
10
VREF = 0.62V
0
VEN = VIN
0.00
1000
3.5
5.5
0.60
5.5
VPG THRESHOLD/VREF (%)
ENABLE INPUT CURRENT (µA)
2400
3.0
5.0
1.50
2600
2.5
0.80
Enable Input Current
vs. Input Voltage
2800
1200
5.0
Rising
1.00
INPUT VOLTAGE (V)
Switching Frequency
vs. Input Voltage
1400
4.5
0.00
2.5
INPUT VOLTAGE (V)
3000
4.0
VOUT = 1.8V
0.0%
4.0
3.5
Enable Threshold
vs. Input Voltage
1.20
ENABLE THRESHOLD (V)
1.2%
3.5
3.0
INPUT VOLTAGE (V)
1.4%
CURRENT LIMIT (A)
OUTPUT REGULATION (%)
3.5
10
3.0
0.608
VOUT = 1.8V
Current Limit
vs. Input Voltage
1.6%
2.5
0.616
INPUT VOLTAGE (V)
Output Regulation
vs. Input Voltage
0.2%
0.624
0.600
2.5
5.5
0.632
VEN = 0V
0.0
2.5
SWITCHING FREQUENCY (kHz)
Feedback Voltage
vs. Input Voltage
8.0
SHUTDOWN CURRENT (µA)
50
SUPPLY CURRENT (mA)
VIN Shutdown Current
vs. Input Voltage
VIN Operating Supply Current
vs. Input Voltage
2.5
5.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
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Micrel Inc.
MIC23201
Typical Characteristics (Continued)
SHUTDOWN CURRENT (µA)
VOUT = 1.8V
IOUT = 0A
SWITCHING
30
20
10
0
-25
0
0.640
25
50
75
100
VIN = 3.3V
8
IOUT = 0A
7
VEN/DLY = 0V
5
4
3
2
2.8
2.7
Rising
2.6
2.5
2.4
Falling
2.3
1
2.2
-25
0
25
50
75
100
125
-50
-25
0
25
50
TEMPERATURE (°C)
TEMPERATURE (°C)
Feedback Voltage
vs. Temperature
Load Regulation
vs. Temperature
Line Regulation
vs. Temperature
2.0%
0.624
0.616
VIN = 3.3V
0.608
VOUT = 1.8V
1.6%
1.4%
1.2%
1.0%
0.8%
0.6%
VIN = 3.3V
0.4%
VOUT = 1.8V
0.2%
0.600
0
25
50
75
100
125
VOUT = 1.8V
0.00%
-0.50%
-1.00%
-1.50%
IOUT = 0A to 2A
0.0%
-25
-2.00%
-50
-25
TEMPERATURE (°C)
0
25
50
75
100
125
-50
TEMPERATURE (°C)
Switching Frequency
vs. Temperature
-25
0
25
50
75
100
125
TEMPERATURE (°C)
Current Limit
vs. Temperature
Enable Threshold
vs. Temperature
3000
125
VIN = 2.7V to 5.5V
LINE REGULATION (%)
0.632
100
0.50%
1.8%
-50
75
TEMPERATURE (°C)
IOUT = 0A
1.20
10
VIN = 3.3V
2800
ENABLE THRESHOLD (V)
SWITCHING FREQUENCY (kHz)
2.9
6
-50
125
LOAD REGULATION (%)
FEEDBACK VOLTAGE (V)
9
0
-50
VIN UVLO Threshold
vs. Temperature
3.0
2600
2400
2200
2000
1800
1600
VIN = 3.3V
1400
VOUT = 1.8V
1200
1.10
CURRENT LIMIT (A)
SUPPLY CURRENT (mA)
VIN =3.3V
40
VIN Shutdown Current
vs. Temperature
10
50
VIN THRESHOLD (V)
VIN Operating Supply Current
vs. Temperature
1.00
Rising
0.90
Falling
0.80
8
6
4
2
VIN = 3.3V
VOUT = 1.8V
IOUT = 0A
1000
-50
-25
0
25
50
75
TEMPERATURE (°C)
August 2012
100
125
0
0.70
-50
-25
0
25
50
75
TEMPERATURE (°C)
5
100
125
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
M9999-082912-A
Micrel Inc.
MIC23201
Typical Characteristics (Continued)
Enable Input Current
vs. Temperature
Feedback Voltage
vs. Output Current
0.00%
0.80
0.60
0.40
VIN = 3.3V
VEN = VIN
0.20
0.640
0.630
0.620
0.610
VIN = 3.3V
0.600
-25
0
25
50
75
100
0.5
TEMPERATURE (°C)
2600
80
EFFICIENCY (%)
SWITCHING FREQUENCY (kHz)
90
2400
2200
2000
1800
1600
1.5
1000
1.0
1.5
2.0
70
60
50
2.0
70
60
50
40
30
20
VIN = 3.3V
VIN = 5V
10
0
0.6
1.2
1.8
2.4
3
0
0.6
1.2
1.8
2.4
3
OUTPUT CURRENT (A)
Output Voltage
vs. Load Current
VOUT Rise Time vs. CSS
1000000
70
5.0VIN
50
40
30
20
10
100000
1.600
1.400
RISE TIME (µs)
OUTPUT VOLTAGE (V)
1.800
80
1.200
1.000
0.800
0.600
0.400
0
1
1.5
2
1000
100
VIN = 3.3V
VOUT = 1.8V
0.000
OUTPUT CURRENT (A)
10000
10
VIN = 3.3A
0.200
VOUT = 1.8V
August 2012
1.5
3.6V
3.3V
2.7V
2.5V
1.8V
1.5V
1.2V
0.95V
OUTPUT CURRENT (A)
3.3VIN
1.0
100
30
2.000
0.5
0.5
Efficiency (VIN = 5V)
vs. Output Current
40
0
100
0
-1.60%
80
Efficiency
vs. Output Current
60
-1.40%
OUTPUT CURRENT (A)
2.5V
1.8V
1.5V
1.2V
0.95V
OUTPUT CURRENT (A)
90
-1.20%
0.0
0
0.5
-1.00%
90
10
VOUT = 1.8V
0.0
-0.80%
2.0
20
VIN = 3.3V
1200
1.0
Efficiency (VIN = 3.3V)
vs. Output Current
100
2800
1400
V OUT = 1.8V
-0.60%
OUTPUT CURRENT (A)
Switching Frequency
vs. Output Current
3000
V IN = 2.7V to 5.5V
-0.40%
-2.00%
0.0
125
EFFICIENCY (%)
-50
-0.20%
-1.80%
VOUT = 1.8V
0.00
EFFICIENCY (%)
LINE REGULATION (%)
0.650
FEEDBACK VOLTAGE (V)
ENABLE INPUT CURRENT (µA)
1.00
Line Regulation
vs. Output Current
0.0
1.0
2.0
3.0
LOAD CURRENT (A)
6
4.0
5.0
1
100
VOUT = 1.8V
1000
10000
100000
1000000
CSS (pF)
M9999-082912-A
Micrel Inc.
MIC23201
Typical Characteristics (Continued)
Case Temperature* (VIN = 3.3V)
vs. Output Current
Case Temperature* (VIN = 5.0V)
vs. Output Current
100
DIE TEMPERATURE (°C)
DIE TEMPERATURE (°C)
100
80
60
40
20
VIN = 3.3V
80
60
40
20
VIN = 5V
VOUT = 1.8V
VOUT = 1.8V
0
0
0.0
0.5
1.0
1.5
OUTPUT CURRENT (A)
2.0
0.0
0.5
1.0
1.5
2.0
OUTPUT CURRENT (A)
Die Temperature* : The temperature measurement was taken at the hottest point on the MIC23201 case and mounted on a 1.4-square
inch PCB (see Thermal Measurements section). Actual results will depend upon the size of the PCB, ambient temperature, and
proximity to other heat-emitting components.
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Micrel Inc.
MIC23201
Functional Characteristics
August 2012
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Micrel Inc.
MIC23201
Functional Characteristics (Continued)
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MIC23201
Functional Characteristics (Continued)
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Micrel Inc.
MIC23201
Functional Diagram
Figure 1. Simplified MIC23201 Functional Block Diagram
voltage from overshooting at start up. Do not leave this
pin floating.
Functional Description
VIN
The input supply (VIN) provides power to the internal
MOSFETs for the switch mode regulator along with the
internal control circuitry. The VIN operating range is 2.7V
to 5.5V so an input capacitor, with a minimum voltage
rating of 6.3V, is recommended. Due to the high
switching speed, 22µF bypass capacitor placed close to
VIN and the power ground (PGND) pin is required. Refer
to the layout recommendations for details.
SVIN
The input supply (SVIN) provides power to internal
control circuitry. This pin is connected externally to the
VIN pin. A 2.2µF ceramic capacitor from the SVIN pin to
AGND must be placed next to the IC.
SW
The switch (SW) connects directly to one end of the
inductor and provides the current path during switching
cycles. The other end of the inductor is connected to the
load, SNS pin and output capacitor. Due to the high
speed switching on this pin, the switch node should be
routed away from sensitive nodes whenever possible.
SS
The soft start (SS) pin is used to control the output
voltage ramp up time. The approximate equation for the
ramp time in seconds is 270x103 x ln(10) x CSS. For
example, for a CSS = 470pF, Trise ~ 300µs. See the
Typical Characteristics curve for a graphical guide. The
minimum recommended value for CSS is 100pF.
EN
A logic high signal on the enable pin activates the output
voltage of the device. A logic low signal on the enable
pin deactivates the output and reduces supply current to
0.01µA. MIC23201 features built-in soft-start circuitry
that reduces in-rush current and prevents the output
August 2012
SNS
The sense (SNS) pin is connected to the output of the
device to provide feedback to the control circuitry. The
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Micrel Inc.
MIC23201
the internal 0.62V reference within the regulation loop.
The output voltage can be programmed using the
following equation:
SNS connection should be placed close to the output
capacitor. Refer to the layout recommendations for more
details.
AGND
The analog ground (AGND) is the ground path for the
biasing and control circuitry. The current loop for the
signal ground should be separate from the power ground
(PGND) loop. Refer to the layout recommendations for
more details.
R1
VOUT VREF 1
R2
where:
R1 is the top resistor, R2 is the bottom resistor. The
output voltage can be adjusted from 0.95V to 3.6V.
PGND
The power ground pin is the ground path for the high
current. The current loop for the power ground should be
as small as possible and separate from the analog
ground (AGND) loop as applicable. Refer to the layout
recommendations for more details.
FB
The FB pin is regulated to 0.62V. A resistor divider
connecting the feedback to the output is used to adjust
the desired output voltage. A resistor divider network is
connected to this pin from the output and is compared to
August 2012
PG
The power good (PG) pin is an open drain output which
indicates logic high when the output voltage is typically
above 87% of its steady state voltage. A pull-up resistor
of more than 5kΩ should be connected from PG to VOUT.
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MIC23201
1 VOUT /VIN
I PEAK IOUT VOUT
2 f L
Application Information
The MIC23201 is a high performance DC/DC step down
regulator offering a small solution size. Supporting an
output current up to 2A inside a tiny 3mm x 3mm MLF
package and requiring only three external components,
the MIC23201 is able to maintain high efficiency
throughout the entire load range while providing ultrafast load transient response. The following sections
provide additional device application information.
As shown by the calculation above, the peak inductor
current is inversely proportional to the switching
frequency and the inductance; the lower the switching
frequency or the inductance the higher the peak current.
As input voltage increases, the peak current also
increases.
The size of the inductor depends on the requirements of
the application. Refer to the Typical Application Circuit
and Bill of Materials for details.
DC resistance (DCR) is also important. While DCR is
inversely proportional to size, DCR can represent a
significant efficiency loss. Refer to the Efficiency
Considerations.
Input Capacitor
A minimum of 4.7µF ceramic capacitor or greater should
be placed close to the VIN pin and PGND / GND pin for
bypassing but the recommended value of input capacitor
is 22µF. A X5R or X7R temperature rating is
recommended for the input capacitor. Y5V temperature
rating capacitors, aside from losing most of their
capacitance over temperature, can also become
resistive at high frequencies. This reduces their ability to
filter out high frequency noise.
Compensation
The MIC23201 is designed to be stable with a 1µH to
2.2µH inductor with a minimum of 4.7µF ceramic (X5R)
output capacitor.
Output Capacitor
The MIC23201 was designed for use with a minimum of
4.7µF or greater ceramic output capacitor. Increasing the
output capacitance will lower output ripple and improve
load transient response but could increase solution size
or cost. The recommended value of output capacitor is
22µF. A low equivalent series resistance (ESR) ceramic
output capacitor is recommended based upon
performance, size and cost. Both the X7R or X5R
temperature rating capacitors are recommended. The
Y5V and Z5U temperature rating capacitors are not
recommended due to their wide variation in capacitance
over temperature and increased resistance at high
frequencies.
Inductor Selection
When selecting an inductor, it is important to consider
the following factors (not necessarily in the order of
importance):
Inductance
Rated current value
Size requirements
DC resistance (DCR)
The MIC23201 was designed for use with a 1µH to
2.2µH inductor. For faster transient response, a 1µH
inductor will yield the best result. For lower output ripple,
a 2.2µH inductor is recommended.
Maximum current ratings of the inductor are generally
given in two methods; permissible DC current and
saturation current. Permissible DC current can be rated
either for a 40°C temperature rise or a 10% to 20% loss
in inductance. Ensure the inductor selected can handle
the maximum operating current. When saturation current
is specified, make sure that there is enough margin so
that the peak current does not cause the inductor to
saturate. Peak current can be calculated as follows:
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MIC23201
where:
Efficiency Considerations
Efficiency is defined as the amount of useful output
power, divided by the amount of power supplied.
V
I
Efficiency % OUT OUT
VIN IIN
PDISS is the power dissipated within the MLF
package. θJA is a combination of junction-to-case
thermal resistance (θJC) and Case-to-Ambient
thermal resistance (θCA), since thermal resistance of
the solder connection from the EPAD to the PCB is
negligible, so θJA = θJC + θCA.
TAMB is the operating ambient temperature.
100
Maintaining high efficiency serves two purposes. It
reduces power dissipation in the power supply, reducing
the need for heat sinks and thermal design
considerations and it reduces consumption of current for
battery powered applications. Reduced current draw
from a battery increases the devices operating time and
is critical in hand held devices.
There are two types of losses in switching converters;
DC losses and switching losses. DC losses are simply
the power dissipation of I2R. Power is dissipated in the
high side switch during the on cycle. Power loss is equal
to the high side MOSFET RDSON multiplied by the RMS
Switch Current squared. During the off cycle, the low
side N-channel MOSFET conducts, also dissipating
power. Device operating current also reduces efficiency.
The product of the quiescent (operating) current and the
supply voltage represents another DC loss. The current
required driving the gates on and off at a constant 2MHz
frequency and the switching transitions make up the
switching losses.
All but the inductor losses are inherent to the device. In
which case, inductor selection becomes increasingly
critical in efficiency calculations. As the inductors are
reduced in size, the DC resistance (DCR) can become
quite significant. The DCR losses can be calculated as
follows:
Thermal Measurements
Measuring the IC’s case temperature is recommended to
ensure it is within its operating limits. Although this might
seem like a very elementary task, it is easy to get
erroneous results. The most common mistake is to use
the standard thermal couple that comes with a thermal
meter. This thermal couple wire gauge is large, typically
22 gauge, and behaves like a heatsink, resulting in a
lower case measurement.
Two methods of temperature measurement are using a
smaller thermal couple wire or an infrared thermometer.
If a thermal couple wire is used, it must be constructed
of 36 gauge wire or higher then (smaller wire size) to
minimize the wire heat-sinking effect. In addition, the
thermal couple tip must be covered in either thermal
grease or thermal glue to make sure that the thermal
couple junction is making good contact with the case of
the IC. Omega brand thermal couple (5SC-TT-K-36-36)
is adequate for most applications.
Wherever possible, an infrared thermometer is
recommended. The measurement spot size of most
infrared thermometers is too large for an accurate
reading on a small form factor ICs. However, an IR
thermometer from Optris has a 1mm spot size, which
makes it a good choice for measuring the hottest point
on the case. An optional stand makes it easy to hold the
beam on the IC for long periods of time.
PDCR = IOUT2 x DCR
From that, the loss in efficiency due to inductor
resistance can be calculated as follows:
VOUT IOUT
Efficiency Loss 1
VOUT IOUT PDCR
100
Efficiency loss due to DCR is minimal at light loads and
gains significance as the load is increased. Inductor
selection becomes a trade-off between efficiency and
size in this case.
Thermal Considerations
The MIC23201 is provided in a 3mm x 3mm MLF
package – a package that has very good thermalperformance This package maximizes heat transfer from
the junction to the exposed pad (EP), which connects to
the ground plane. The size of the ground plane attached
to the exposed pad determines the overall thermal
resistance from the junction to the ambient air
surrounding the printed circuit board. The junction
temperature for a given ambient temperature can be
calculated using:
TJ = TAMB + PDISS JA
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MIC23201
(FB) pin.
PCB Layout Guidelines
Warning!!! To minimize EMI and output noise, follow
these layout recommendations.
PCB Layout is critical to achieve reliable, stable and
efficient performance. A ground plane is required to
control EMI and minimize the inductance in power,
signal and return paths. Thickness of the copper planes
is also important in terms of dissipating heat. The 2
ounce copper thickness is adequate from thermal point
of view and also thick copper plain helps in terms of
noise immunity. Keep in mind thinner planes can be
easily penetrated by noise
The inductor can be placed on the opposite side of
the PCB with respect to the IC. It does not matter
whether the IC or inductor is on the top or bottom as
long as there is enough air flow to keep the power
components within their temperature limits. The
input and output capacitors must be placed on the
same side of the board as the IC.
Output Capacitor
The following guidelines should be followed to insure
proper operation of the MIC23201 converter.
Use a wide trace to connect the output capacitor
ground terminal to the input capacitor ground
terminal.
Phase margin will change as the output capacitor
value and ESR changes. Contact the factory if the
output capacitor is different from what is shown in
the BOM.
IC
Place the IC close to the point of load (POL).
Use fat traces to route the input and output power
lines.
The signal ground pin (AGND) must be connected
directly to the ground planes.
Signal and power grounds should be kept separate
and connected at only one location.
To minimize noise, place a ground plane underneath
the inductor.
The feedback trace should be separate from the
power trace and connected as close as possible to
the output capacitor. Sensing a long high current
load trace can degrade the DC load regulation.
RC Snubber
Place the RC snubber on either side of the board
and as close to the SW pin as possible.
Input Capacitor
Place the input capacitor next to the power pins.
Place the input capacitors on the same side of the
board and as close to the IC as possible.
Keep both the VIN pin and PGND connections short.
Place several vias to the ground plane close to the
input capacitor ground terminal.
Use either X7R or X5R dielectric input capacitors.
Do not use Y5V or Z5U type capacitors.
Do not replace the ceramic input capacitor with any
other type of capacitor. Any type of capacitor can be
placed in parallel with the input capacitor.
If a Tantalum input capacitor is placed in parallel
with the input capacitor, it must be recommended for
switching regulator applications and the operating
voltage must be derated by 50%.
In “Hot-Plug” applications, a Tantalum or Electrolytic
bypass capacitor must be used to limit the overvoltage spike seen on the input supply with power is
suddenly applied.
Inductor
Keep the inductor connection to the switch node
(SW) short.
Do not route any digital lines underneath or close to
the inductor.
Keep the switch node (SW) away from the feedback
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MIC23201
Typical Application Circuit
Bill of Materials
Item
C1, C2
C3
Part Number
Manufacturer
GRM31CR71A226KE15L
Murata
AVX
GRM188R71H471KA01D
Murata
C1608X7R1H471K
TDK
VLS4012T-1R0N1R6
CRCW0201301KFKED
R2
ERJ-1GEF1583C
R3, R4
CRCW020110K0JNED
R5
ERJ-3GEYJ2R2V
R6
CRCW020149R9FKED
U1
MIC23201YML
Ceramic Capacitor, 470pF, 50V, X7R, Size 0603
1
Not Fitted (NF)
1
Ceramic Capacitor, 2.2µ F, 6.3V, X5R, Size 0603
Murata
C1608X5R0J225K
R1
2
AVX
GRM188R60J225KE19D
L1
Ceramic Capacitor, 22µF, 10V, X7R, Size 1206
(3)
06036D225KAT2A
C5
Qty.
(2)
06035C471KAT2A
C4
Description
(1)
TDK
TDK
Vishay/Dale(4)
Panasonic - ECG
(5)
Vishay/Dale
1µH, 2.5A, 60mΩ, L4.0mm x W4.0mm x H1.2mm
1
Resistor, 301k Ω, Size 0603
1
Resistor,158k Ω, Size 0603
1
Resistor,10k Ω, Size 0603
2
Panasonic - ECG
Resistor, 2.2 Ω, Size 0603
Vishay/Dale
Resistor, 49.9Ω, Size 0603
Micrel, Inc.(6)
2MHz 2A Buck Regulator with Hyper Speed Control Mode
1
Notes:
1. Murata : www.murata.com.
2. AVX: www.avx.com.
3. TDK: www.tdk.com.
4. Vishay: www.vishay.com.
5. Panasonic: www.industrial.panasonic.com.
6. Micrel, Inc.: www.micrel.com.
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MIC23201
PCB Layout
Figure 11. MIC23201 Evaluation Board Top Layer
Figure 12. MIC23201 Evaluation Board Mid-Layer 1 (Ground Plane)
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MIC23201
PCB Layout (Continued)
Figure 13. MIC23201 Evaluation Board Mid-Layer 2
Figure 14. MIC23201 Evaluation Board Bottom Layer
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MIC23201
Recommended Land Pattern
ALL UNITS ARE IN mm, TOLERANCE 0.05, IF NOT NOTED
LP # MLF33D-10LD-LP-1
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MIC23201
Package Information
10-Pin 3mm x 3mm MLF (ML)
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
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2012 Micrel, Incorporated.
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