MIC2225
2MHz 600mA Synchronous Buck
Regulator with 300mA LDO
MLF and MicroLeadFrame are registered trademarks of 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
February 2008
M9999-022008-D
General Description
The Micrel MIC2225 is a dual output regulator featuring a
high efficiency 2MHz PWM synchronous buck (step-down)
regulator and a 300mA LDO. The MIC2225 is an ultra-low
noise, small size, and high efficiency solution for portable
power applications, providing core and I/O supply rails for
applications like application processors, camera DSPs and
multimedia chipsets.
In PWM mode, the MIC2225 operates with a constant
2MHz frequency. The MIC2225 switching regulator
operates from 2.7V to 5.5V input and features internal
power MOSFETs that can supply up to 600mA output
current in PWM mode.
The MIC2225 is available in the 10-pin 2mm x 2mm Thin
MLF
®
package with a junction operating range from –40°C
to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
DC-DC Converter
• 2.7 to 5.5V supply voltage
• 2MHz PWM mode
• Output current to 600mA
• >95% efficiency
• 100% maximum duty cycle
• Fixed output voltage option down to 1V
• Ultra-fast transient response
• Stable with 2.2µF ceramic output capacitor
• Fully integrated MOSFET switches
• Micropower shutdown (1mA in shutdown)
• Thermal shutdown and current limit protection
• Pb-free 10-pin 2mm x 2mm Thin MLF
®
package
• –40°C to +125°C junction temperature range
LDO
• V
IN
range 2.7V to 5.5V
• 300mA output current
• Output voltage down to 0.8V
• Thermal shutdown protection
• Current limit protection
Applications
• Cellular phones
• PDAs
• USB peripherals
___________________________________________________________________________________________________________
Typical Application
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6
LOAD CURRENT (A)
1.8V Efficiency @ 25°C
2.7V
IN
5.5V
IN
3.6V
IN
Micrel, Inc. MIC2225
February 2008
2 M9999-022008-D
Ordering Information
Part Number Marking
Code Voltage* Temperature Range Package Lead Finish
MIC2225-4KYMT 4TK 1.2V/2.6V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
MIC2225-4MYMT 4TM 1.2V/2.8V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
MIC2225-4OYMT 4TO 1.2V/2.9V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
MIC2225-4SYMT 4TS 1.2V/3.3V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
MIC2225-G4YMT GT4 1.8V/1.2V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
MIC2225-GFYMT GTF 1.8V/1.5V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
MIC2225-GJYMT GTJ 1.8V/2.5V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
MIC2225-GMYMT GTM 1.8V/2.8V –40° to +125°C 10-Pin 2x2 Thin MLF
®
Pb-Free
Note:
MLF® is a GREEN RoHS compliant package. Lead finish is NiPdAu. Mold compound is Halogen Free.
Other voltage options available. Please contact Micrel for details.
* Refers to nominal output voltage of DC/DC and LDO respectively.
Pin Configur ation
FB EN5
1
A
GND
LDO
BIAS
AVIN
10 PGND
SW
VIN
ENLDO
9
8
7
2
3
4
6
10-Pin 2mm x 2mm Thin MLF
®
(MT)
Micrel, Inc. MIC2225
February 2008
3 M9999-022008-D
Pin Description
Pin Number Pin Name Pin Function
1 AGND Analog (signal) Ground.
2 LDO LDO Output (Output): Connect to a 2.2µF output capacitor.
3 BIAS
Internal circuit bias supply. Must be de-coupled to signal ground with a 0.1µF
capacitor and should not be loaded.
4 AVIN
Analog Supply Voltage (Input): Supply voltage for the analog control circuitry
and LDO input power. Requires bypass capacitor to GND. It must be tied to
VIN.
5 FB
Feedback. Input to the error amplifier. For the Adjustable option, connect to the
external resistor divider network to set the output voltage. For fixed output
voltage options, connect to V
OUT
and an internal resistor network sets the output
voltage.
6 EN
Enable (Input). Logic low will shut down the switching regulator reducing the
quiescent current to less than 5µA.
7 ENLDO
Enable LDO (Input): Logic low will shut down the LDO, reducing the quiescent
current to less than 5µA.
8 VIN Supply Voltage (Input): Supply voltage for the internal switches and drivers.
9 SW Switch (Output): Internal power MOSFET output switches.
10 PGND Power Ground.
Micrel, Inc. MIC2225
February 2008
4 M9999-022008-D
Absolute Maximum Ratings(1)
Supply Voltage (V
IN
).......................................................+6V
Output Switch Voltage (V
SW
) ..........................................+6V
Output Switch Current (I
SW
)..............................................1A
Logic Input Voltage (V
EN
,V
LOWQ
)........................ –0.3V to V
IN
Storage Temperature (T
s
) .........................–60°C to +150°C
ESD Rating
(3)
.................................................................. 2kV
Operating Ratings(2)
Supply Voltage (V
IN
)..................................... +2.7V to +5.5V
Logic Input Voltage (V
EN
,V
LOWQ
)........................ –0.3V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Junction Thermal Resistance
Thin MLF-10L (θ
JA
) ............................................90°C/W
Electrical Characteristics DC/DC(4)
V
EN
= V
IN
= 3.6V, L = 2.2µH; C
OUTDC/DC
= 2.2µF, C
LDO
= 2.2µF; I
OUTDC/DC
= 100mA; C
BIAS
= 0.1µF
V
ENLDO
= 0V; T
J
= 25°C, bold values indicate –40°C < T
J
< +125°C; unless noted.
Parameter Condition Min Typ Max Units
UVLO Threshold Rising input voltage during turn-on 2.45 2.55 2.65 V
UVLO Hysteresis 70 mV
Switcher Ground Pin Current ENLDO = 0V, V
FB
= GND ; I
L
=0mA 850 1100 µA
LDO Ground Pin Current EN = 0V 67 110 µA
Ground Pin Current in
Shutdown
EN +ENLDO = 0V 0.2 5 µA
Over-temperature Shutdown 160 °C
Over-temperature Shutdown
Hysteresis
23
°C
Logic Low 0.2 V Enable Input Voltage
Logic High 1.0 V
V
IL
< 0.2V 0.1 1 µA Enable Input Current
V
IH
> 1.0V 0.1 1 µA
Turn-on Time I
LOAD
= 5mA 50 µs
Fixed Output Voltages Nominal V
OUT
tolerance Io=50mA –2
–3
+2
+3
%
%
Current Limit in PWM Mode V
FB
= 0.9*V
NOM
0.675 0.95 A
Output Voltage Line Regulation V
IN
= 2.7V to 5.5V, I
LOAD
= 100mA 0.12 1 %
%
Output Voltage Load Regulation 20mA < I
LOAD
< 300mA 0.2 1.5 %
Maximum Duty Cycle V
FB
≤ 0.4V 100 %
PWM Switch ON-Resistance I
SW
= 150mA; V
FB
= 0.7V
FB_NOM
I
SW
= -150mA; V
FB
= 1.1V
FB_NOM
0.4
0.4
Ω
Ω
Oscillator Frequency 1.8 2 2.2 MHz
Micrel, Inc. MIC2225
February 2008
5 M9999-022008-D
Electrical Characteristics LDO(4)
C
OUTLDO
= 2.2µF, I
OUTLDO
= 100µA; T
J
= 25°C, bold values indicate –40°C < T
J
< +125°C; unless noted.
Parameter Condition Min Typ Max Units
Input Voltage 2.7 5.5 V
Variation from nominal V
OUT
–2.0 +2.0 % Output Voltage Accuracy
Variation from nominal V
OUT
; –40°C to +125°C –3.0 +3.0 %
Line Regulation V
IN
= V
OUT
+1V to 5.5V; I
OUT
= 100µA 0.2 %
Turn-on Time I
LOAD
= 300mA 30 µs
Load Regulation I
OUT
= 100µA to 300mA @ V
IN
= V
OUT
+ 1 0.70 %
Dropout Voltage, Note 5 I
OUT
= 300mA @ V
IN
= 2.7V 210 mV
Ripple Rejection f = 1kHz; C
OUT
= 2.2µF
f = 20kHz; C
OUT
= 2.2µF
43
17
dB
dB
Current Limit V
OUT
= 0V 400 mA
Output Voltage Noise C
OUT
= 2.2µF, 10Hz to 100kHz 470 µV
RMS
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. Dropout voltage is defined as the input-to-output differential at which the output voltage drops 2% below its nominal value that is initially measured at
a 1V differential. For outputs below 2.7V, the dropout voltage is the input-to-output voltage differential with a minimum input voltage of 2.7V.
Micrel, Inc. MIC2225
February 2008
6 M9999-022008-D
Typical Characteristics (DC-DC)
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6
LOAD CURRENT (A)
1.2V Efficiency @ –40°C
2.7V
IN
5.5V
IN
3.6V
IN
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6
LOAD CURRENT (A)
1.2V Efficiency @ 25°C
2.7VIN
5.5V
IN
3.6V
IN
0
10
20
30
40
50
60
70
80
90
100
0 0.1 0.2 0.3 0.4 0.5 0.6
LOAD CURRENT (A)
1.2V Efficiency @ 70°C
2.7V
IN
5.5V
IN
3.6V
IN
0
25
50
75
100
125
150
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Quiescent Current
vs. Input Voltage
V
OUT
= 1.2V
LOAD = 0
ENLDO = 0V
EN = V
IN
0
200
400
600
800
1000
1200
Quiescent Current
vs. Load Current
V
OUT
= 1.2V
EN = V
IN
ENLDO = 0V
40 60
LOAD CURRENT (mA)
30 50
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Enable Threshold
vs. Input Voltage
V
OUT
= 1.19V
ENLDO = 5V
0
10
20
30
40
50
60
70
80
90
100
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Turn-On Time
vs. Input Voltage
VOUT = 1.19V
VLDO = 2.8V
ENLDO = 5V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Peak Current Limit
vs. Input Voltage
V
OUT
= 1.2V
EN = ENLDO = V
IN
1.5
1.7
1.9
2.1
2.3
2.5
2.7
2.9
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Frequency
vs. Input Voltage
VOUT = 1.2V
LOAD = 0
ENLDO = VIN
Micrel, Inc. MIC2225
February 2008
7 M9999-022008-D
Typical Characteristics ( LDO)
0
10
20
30
40
50
60
70
100 1K 10K 100K
FREQUENCY (Hz)
PSRR
10mA
300mA
100mA
VIN = 1.7V
VOUT = 2.8V
COUT = 2.2µF
0
10
20
30
40
50
60
70
80
90
012345
INPUT VOLTAGE (V)
Quiescent Current
vs. Input Voltage
ENLDO = VIN
0mA
100mA
60mA
60
62
64
66
68
70
72
74
76
78
80
0.025 0.075 0.125 0.175 0.225 0.275
LOAD CURRENT (A)
Quiescent Current
vs. Load Current
V
IN
= 3.6V
ENLDO = V
IN
0
25
50
75
100
125
-40 -20 0 100
TEMPERATURE (°C)
12020 40 60 80
Quiescent Current
vs. Temperatu re
1mA
100mA
50mA
VIN = 3.6V
ENLDO = VIN
2.50
2.55
2.60
2.65
2.70
2.75
2.80
2.85
2.90
2.95
3.00
0.025 0.075 0.125 0.175 0.225 0.275
LOAD CURRENT (A)
Output Vol tage
vs. Load Current
VIN = 3.6V
ENLDO = VIN
2.55
2.65
2.75
2.85
2.95
-40 -20 0 100
TEMPERATURE (°C)
12020 40 60 80
2.50
2.60
2.70
2.80
2.90
3.00
Output Voltage
vs. Temperature
V
IN
= 3.6V
ENLDO = V
IN
Load = 1mA
2.66
2.68
2.72
2.74
2.76
2.78
2.8
2.82
2.84
2.86
2.70
-40 -20 0 100
TEMPERATURE (°C)
12020 40 60 80
Output Voltage
vs. Temperatu re
VIN = 3.6V
ENLDO = VIN
Load = 10mA
0
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
0 0.05 0.1 0.15 0.2 0.25 0.3
LOAD CURRENT (A)
Dropout Voltage
vs. Load Curren t
VIN = 3.6V
ENLDO = VIN
0
10
20
30
40
50
-40 -20 0 100
TEMPERATURE (°C)
12020 40 60 80
Dropout Volt age
vs. Temperature
1mA
50mA
10mA
ENLDO = V
IN
25mA
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Peak Current Limit
vs. Input Voltage
EN = ENLDO = VIN
0
5
10
15
20
25
30
35
40
45
50
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Turn-On Time
vs. Input Voltage
ENLDO = VIN
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Enable Threshold
vs. Input Voltage
LDO = 2.8V
Micrel, Inc. MIC2225
February 2008
8 M9999-022008-D
Typical Characteristics ( LDO) continued
0
0.5
1.0
1.5
2.0
2.5
3.0
10
FREQUENCY (Hz)
Output Noise
Spectral Density
100 1K 10K 100K 1M
VIN = 3.6V
VOUT = 3.3V
COUT = 2.2µF
CBYP = 0.1µF
Noise(10Hz–100kHz) = 169µV
RMS
Micrel, Inc. MIC2225
February 2008
9 M9999-022008-D
Functional Characteristics
Micrel, Inc. MIC2225
February 2008
10 M9999-022008-D
Functional Diagram
VIN
AVIN
BIAS
EN
ENLDO
SW
V
OUT1
C
OUT1
FB
LDO
PGND
Enable and
Control Logic
PWM
Control
Anti-Shoot
Through
P-Channel
Current Limit
6
LDO
Current
Limit
SGND
LDO Block
1.0V
1.0V
Soft
Start
Bias,
UVLO,
Thermal
Shutdown
HSD
LSD
N-Channel
Current Limit
EA
EA
V
OUT2
C
OUT2
MIC2225 Block Diagram
Micrel, Inc. MIC2225
February 2008
11 M9999-022008-D
Functional Description
VIN
VIN provides power to the MOSFETs for the switch
mode regulator section, along with the current limiting
sensing. Due to the high switching speeds, it is
recommended that an 1µF capacitor be placed close to
VIN and the power ground (PGND) pin for bypassing.
Please refer to layout recommendations.
AVIN
Analog VIN (AVIN) provides power to the LDO section
and the bias through an internal 6Ω resistor. AVIN and
VIN must be tied together. Careful layout should be
considered to ensure high frequency switching noise
caused by VIN is reduced before reaching AVIN.
LDO
The LDO pin is the output of the linear regulator and
needs to be connected to a 2.2µF output capacitor.
EN
The enable pin provides a logic level control of the
output. In the off state, the supply current of the device is
greatly reduced (typically <1µA). Also, in the off state,
the output drive is placed in a "tri-stated" condition,
wherein both the high side P-channel MOSFET and the
low-side N-channel are in an “off” or non-conducting
state. Do not drive the enable pin above the supply
voltage.
ENLDO
The enable pin provides a logic level control of the LDO
output. In the off state, supply current of the device is
greatly reduced (typically <1µA). Do not drive the enable
pin above the supply voltage.
BIAS
The BIAS pin supplies the power to the internal power to
the control and reference circuitry. The bias is powered
from AVIN through an internal 6Ω resistor. A small 0.1µF
capacitor is recommended for bypassing.
FB
The feedback pin (FB) provides the control path to
control the output. For fixed output, the controller
output is directly connected to the feedback (FB) pin.
SW
The switch (SW) pin connects directly to the inductor
and provides the switching current necessary to operate
in PWM mode. Due to the high speed switching on this
pin, the switch node should be routed away from
sensitive nodes.
PGND
Power ground (PGND) is the ground path for the high
current PWM mode. The current loop for the power
ground should be as small as possible and separate
from the Analog ground (AGND) loop. Refer to the layout
considerations for more details.
SGND
Signal ground (SGND) 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 considerations for more
details.
Micrel, Inc. MIC2225
February 2008
12 M9999-022008-D
Application Information
The MIC2225 is a 600mA PWM and 300mA LDO dual
power supply. Both PWM output and LDO outputs are
independent and are controlled by EN and ENLDO pins
respectively. These enable pins are logic level
compatible.
Input Capacitor
A minimum 1µF ceramic is recommended on the VIN pin
for bypassing. X5R or X7R dielectrics are recommended
for the input capacitor. Y5V dielectrics loose most of
their capacitance over temperature and are therefore,
not recommended.
A minimum 1µF is recommended for placement close to
the VIN and PGND pins for high frequency filtering.
Smaller case size capacitors are recommended due to
their lower ESR and ESL. Please refer to layout
recommendations for proper layout of the input
capacitor.
Output Capacitor
Even though the MIC2225 is optimized for a 2.2µF
output capacitor, output capacitance can be varied from
1µF to 10µF. The MIC2225 utilizes Type III internal
compensation and utilizes an internal high frequency
zero to compensate for the double pole roll off of the LC
filter. For this reason, larger output capacitors can create
instabilities. X5R or X7R dielectrics are recommended
for the output capacitor. Y5V dielectrics lose most of
their capacitance over temperature and are therefore,
not recommended.
In addition to a 2.2µF, a small 10nF is recommended
close to the load for high frequency filtering. Smaller
case size capacitors are recommended due to there
lower ESR and ESL.
Inductor Selection
The MIC2225 is designed for use with a 2.2µH inductor.
Proper selection should ensure that the inductor can
handle the maximum average and peak currents
required by the load. Maximum current ratings for 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 that 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 will
not saturate the inductor. Peak inductor current can be
calculated as follows:
Lf2
V
V
1V
II
IN
OUT
OUT
OUTPK
××
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−
+=
Micrel, Inc. MIC2225
February 2008 13
M9999-022008-D
PCB Layout Recommendations
Top Layer
Bottom Layer
Note:
The above figures demonstrate the recommended layout for the MIC2225 fixed output option.
Micrel, Inc. MIC2225
February 2008 14
M9999-022008-D
J3
VO1
MIC2225
J5
GND
J1
V
IN
5.5V Max
J2
GND
VIN
AVIN
SW
FB
ENLDO
EN
LDO
PGND
BIAS
AGND
C4
2.2µF/
6.3V
C3
2.2µF/
6.3V
R3
0
C2
0.1µF/
6.3V
L1
0.47µH / 2.2µH
8
4
6
7
3
10 1
2
5
9
J6
EN
R1
10k
J7
ENLDO
C1
2.2µF/
6.3V
J4
VO2
R2
10k
JP1
1X2
21
Schematic Diagram
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1 C1608X5R0J225K TDK
(1)
2.2µF/6.3V, X5R 1
C2 VJ0402Y104KXQCW1BC Vishay Vitramon
(2)
0.1µF/6.3V, X7R 1
C3 C1608X5R0J225K TDK
(1)
2.2µF/6.3V, X5R 1
C4 C1608X5R0J225K TDK
(1)
2.2µF/6.3V, X5R 1
R1 CRCW06031002FKEYE3 Vishay Dale
(2)
10k, 0603, 1/16W, 1% 1
R2 CRCW06031002FKEYE3 Vishay Dale
(2)
10k, 0603, 1/16W, 1% 1
R3 CRCW08050000FKEYE3 Vishay Dale
(2)
0, 0805, 1/8W, 1% 1
L1 CDRH2D11/HPNP-2R2NC Sumida
(3)
2.2µH, 1.1A (Isat) 1
U1 MIC2225-XYMT Micrel, Inc.
(4)
2Mhz PWM Synchronous Buck Regulator
with 300mA LDO 1
Notes:
1. TDK: www.tdk.com
2. Vishay: www.vishay.com
3. Sumida: www.sumida.com
4. Micrel, Inc.: www.micrel.com
Micrel, Inc. MIC2225
February 2008 15
M9999-022008-D
Package Information
10-Pin Thin MLF
®
(MT)
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.
© 2007 Micrel, Incorporated.
