MIC2203 DATA SHEET (11/05/2015) DOWNLOAD

MIC2203
High Efficiency 1MHz Synchronous
Buck Regulator
General Description
Features
The Micrel MIC2203 is a high efficiency 1MHz PWM
synchronous buck switching regulator. The MIC2203
features low noise constant frequency PWM
operation with a low dynamic supply current of
<1mA. The low noise and efficient operation both
make the MIC2203 well suited for sensitive RF, and
audio power applications.
The MIC2203 operates from 2.3V to 5.5V input and
can supply over 300mA of output current with output
voltages down to 0.5V. Additionally, the MIC2203
can be synchronized to an external clock, or multiple
MIC2203s can easily be daisy-chained with the
SYNCLOCK feature.
The MIC2203 has a high loop bandwidth with
corresponding ultra fast transient response times.
This reduces the output capacitor size, and is very
useful when powering applications that require fast
dynamic response such as CPU cores and RF
circuitry in high performance cellular phones and
PDAs.
The MIC2203 is available in 10-pin MSOP and
3mm x 3mm MLF™-10L package options with an
operating junction temperature range from –40ºC to
125ºC.
•
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•
•
•
•
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Input voltage range: 2.3V to 5.5V
Output voltage adjustable down to 0.5V
300mA output current
Constant 1MHz PWM switching frequency
> 95% efficiency
< 1mA switching supply current
< 350µA static quiescent current
< 1µA shutdown current
All-ceramic capacitors
Easily synchronized to external clock
SYNCLOCK feature to daisy chain multiple
devices
• Thermal shutdown and current limit protection
• 10 pin MSOP, and 3mm x 3mm MLF-10L package
options
• –40ºC to +125ºC junction temperature range
Applications
• 802.11 WLAN modules
• MD players
• MP3 players
_____________________________________________________________________
Typical Application
10µH
1.8V
300mA
MIC2203BMM
2.3V to 5.5V
SYNC_IN
1µF
SYNC_OUT
EN
1
10
2
9
3
8
4
7
5
6
R1
10k
2.2µF
10nF
R2
3.83k
High Efficiency Buck Regulator
MicroLead Frame and MLF are trademarks of Amkor Technologies.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax +1 (408) 474-1000 • http://www.micrel.com
December 2004
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MIC2203
Ordering Information
Part Number
Standard
Pb-Free
MIC2203BMM MIC2203YMM
MIC2203BML
MIC2203YML
Output Voltage
Junction Temperature
Range
Package
Adjustable
Adjustable
-40°C to +125°C
-40°C to +125°C
MSOP-10L
3mm x 3mm MLF-10L
Pin Configuration
MLF-10 (ML)
Top View
MSOP-10 (MM)
Pin Description
Pin Number
Pin Name
1
SW
Switch (Output): Internal power MOSFET output switches.
Pin Function
2
VIN
Supply Voltage (Input): Requires a bypass capacitor to GND.
3
SYNC_IN
4
SYNC_OUT
5
EN
A low level EN will power down the device, reducing the quiescent current to
under 1µA.
6
FB
Input to the error amplifier, connect to the external resistor divider network to set
the output voltage.
7
BIAS
Internal circuit bias supply, nominally 2.3V. Must be de-coupled to signal ground
and can have a minimum of external DC loading.
8,9,10
GND
Ground
EP
GND
Exposed backside pad, connect to Ground (MLF option only)
SYNC_IN for the MIC2203, Sync the main switching frequency to a external
clock. Should be tied to ground when not in use.
SYNC_OUT a 50ns wide sync pulse to feed into SYNC_IN on MIC2203.
Can be left open or tied to ground when not used.
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MIC2203
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) .............................................. 6V
Output Switch Voltage (VSW) ................................. 6V
Logic Input Voltage (VEN, VSYNC_IN) .............VIN to –3V
Power Dissipation ............................................Note 5
Storage Temperature (Ts)............... –65°C to +150°C
ESD Rating(3) ........................................................2kV
Supply Voltage (VIN)................................2.3V to 5.5V
Junction Temperature Range ......... –40°C to +125°C
Package Thermal Resistance
MSOP-10L (θJA)..................................... 115°C/W
3mmX3mm MLF-10L (θJA)....................... 60°C/W
Electrical Characteristics(4)
TA = 25°C with VIN = VEN = 3.5V, unless otherwise specified. Bold values indicate –40ºC < TJ < +125ºC
Parameter
Condition
Min
2.3
Supply Voltage Range
Quiescent Current
No Load Supply Current
Typ
Max
Units
5.5
V
VFB = 0.6V (not switching)
320
450
µA
EN = 0V (shutdown)
0.01
1
µA
(switching)
870
MIC2203 [Adjustable]
Feedback Voltage
0.4875
µA
0.5
0.5125
V
Output Voltage Line
Regulation
VOUT < 2V; VIN = 2.3V to 5.5V, ILOAD= 50mA
0.13
0.5
%
Output Voltage Load
Regulation
0mA < ILOAD < 300mA
0.2
0.5
%
2.32
2.6
V
Bias Regulator Output
Voltage
2.2
Maximum Duty Cycle
VFB ≤ 0.4V
100
Current Limit
VFB = 0.4V
0.375
Switch ON-Resistance
ISW = 300mA VFB = 0.4V
ISW = -300mA VFB = 0.6V
Enable Input Current
Sync Frequency Range
0.8
SYNC_IN Threshold
0.7
Sync Minimum Pulse
Width
%
0.6
1.5
A
1.5
1
2.2
1.6
Ω
0.01
2
µA
1.25
MHz
1
1.7
10
SYNC_IN Input Current
V
ns
1
µA
Oscillator Frequency
0.8
1
1.2
MHz
Enable Threshold
0.5
0.7
1.3
V
Enable Hysteresis
Over Temperature
Shutdown
Hysteresis
20
mV
160
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, 1.5k in series with 100pF.
4. Specification for packaged product only.
5. Absolute maximum power dissipation is limited by maximum junction temperature where PD(MAX) = (TJ(MAX) – TA) ÷θJA.
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MIC2203
Typical Characteristics
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MIC2203
Functional Diagram
VIN
CIN
SYNC_OUT
Oscillator
Ramp
Generator
SYNC_IN
BIAS
VIN
Internal
Supply
R1
PWM
Comparator
Error
Amplifier
Driver
VOUT
SW
R2
COUT
0.5V
EN
MIC2203
FB
GND
Figure 1. MIC2203 Block Diagram
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MIC2203
Functional Description
SYNC_OUT
SYNC_OUT is an open collector output that
provides a signal equal to the internal oscillator
frequency. This creates the ability for multiple
MIC2203s to be connected together in a masterslave configuration for frequency matching of the
converters. A typical 10kΩ resistor is recommended
for the pull-up resistor.
VIN
VIN provides power to the output and to the internal
bias supply. The supply voltage range is from 2.3V
to 5.5V. A minimum 1µF ceramic capacitor is
recommended for bypassing the input supply.
Enable
The enable pin provides a logic level control of the
output. In the off state, 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, where 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.
Bias
The bias supply is an internal 2.3V linear regulator
that supplies the internal biasing voltage to the
MIC2203. A 10nF ceramic capacitor is required on
this pin for bypassing. Do not use the bias pin as a
supply. The bias pin was designed to supply internal
power only.
Feedback
The feedback pin provides the control path to control
the output. A resistor divider connecting the
feedback to the output is used to adjust the desired
output voltage. Refer to the feedback section in the
“Applications Information” for more detail.
SYNC_IN
SYNC_IN pin enables the ability to change the
fundamental switching frequency. The SYNC_IN
frequency has a minimum frequency of 800KHz and
a maximum sync frequency of 1.2MHz. Careful
attention should be paid to not driving the SYNC_IN
pin greater than the supply voltage. Although this will
not damage the device, it can cause improper
operation.
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MIC2203
Application Information
Bias Capacitor
Input Capacitor
A small 10nF ceramic capacitor is required to
bypass the bias pin. The use of low ESR ceramics
provides improved filtering for the bias supply.
Efficiency Considerations
Efficiency is defined as the amount of useful output
power, divided by the amount of power consumed.
⎛V ×I
⎞
Efficiency% = ⎜ OUT OUT ⎟ × 100
⎝ VIN × IIN ⎠
A minimum 1µF ceramic capacitor is recommended
on the VIN pin for bypassing. X5R or X7R dielectrics
are recommended for the input capacitor. Y5V
dielectrics, aside from losing most of their
capacitance over temperature, also become resistive at high frequencies. This reduces their ability to
filter out high frequency noise.
Output Capacitor
The MIC2203 was designed specifically for the use
of a 2.2µF ceramic output capacitor. Since the
MIC2203 is voltage mode regulator, the control loop
relies on the inductor and output capacitor for
compensation. For this reason, do not use
excessively large output capacitors. The output
capacitor requires either an X7R or X5R dielectric.
Y5V and Z5U dielectric capacitors, aside from the
undesirable effect of their wide variation in
capacitance over temperature, become resistive at
high frequencies. Using Y5V or Z5U capacitors will
cause instability in the MIC2203.
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 drawn from a battery increases the device’s
operating time, which is critical in hand held devices.
There are two loss terms in switching converters: DC
losses and switching losses. DC losses are simply
2
the power dissipation of I R. Power is dissipated in
the high side switch during the on cycle. Power loss
is equal to the high side MOSFET RDS(ON) multiplied
2
by the (Switch Current) . 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 is another
DC loss. The current required to drive the gates on
and off at a constant 1MHz frequency and the
switching transitions make up the switching losses.
Figure 2 shows an efficiency curve. The non-shaded
portion, from 0mA to 100mA, efficiency losses are
dominated by quiescent current losses, gate drive
and transition losses. In this case, lower supply
voltages yield greater efficiency in that they require
less current to drive the MOSFETs and have
reduced input power consumption.
Total output capacitance should not exceed 3µF.
Inductor Selection
Inductor selection will be determined by the following
(not necessarily in the order of importance):
• Inductance
• Rated current value
• Size requirements
• DC resistance (DCR)
The MIC2203 is designed for use with a 10µH
inductor.
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% 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 that the peak current will not
saturate the inductor.
The size requirements refer to the area and height
requirements that are necessary to fit a particular
design. Please refer to the inductor dimensions on
their datasheet.
DC resistance is also important. While DCR is
inversely proportional to size, DCR can represent a
significant efficiency loss. Refer to the “Efficiency
Considerations” below for a more detailed
description.
December 2004
Figure 2. Efficiency Curve
The shaded region, 100mA to 300mA, efficiency
loss is dominated by MOSFET RDS(ON) and inductor
DC losses. Higher input supply voltages will increase
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MIC2203
the Gate-to-Source threshold on the internal
MOSFETs, reducing the internal RDS(ON). This
improves efficiency by reducing DC losses in the
device. 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:
can create a phase loss at high frequency. This
phase loss degrades transient response by reducing
phase margin. Adding feed-forward capacitance
negates the parasitic capacitive effects of the
feedback pin.
Also, large feedback resistor values increase the
impedance, making the feedback node more
susceptible to noise pick-up. A feed-forward
capacitor would also reduce noise pick-up by
providing a low impedance path to the output.
PL = IOUT 2 × DCR
PWM Operation
The MIC2203 is a pulse width modulation (PWM)
regulator. By controlling the ratio of on-to-off time, or
duty cycle, a regulated DC output voltage is
achieved. As load or supply voltage changes, so
does the duty cycle to maintain a constant output
voltage. In cases where the input supply runs into a
dropout condition, the MIC2203 will run at 100%
duty cycle.
The MIC2203 provides constant switching at 1MHz
with synchronous internal MOSFETs. The internal
MOSFETs include a high-side P-Channel MOSFET
from the input supply to the switch pin and an NChannel MOSFET from the switch pin-to-ground.
Since the low-side N-Channel MOSFET provides the
current during the off cycle, a free wheeling Schottky
diode from the switch node to ground is not required.
PWM control provides fixed frequency operation. By
maintaining a constant switching frequency,
predictable fundamental and harmonic frequencies
are achieved. Other methods of regulation, such as
burst and skip modes, have frequency spectrums
that change with load that can interfere with
sensitive communication equipment.
From that, the loss in efficiency due to inductor
resistance can be calculated as follows:
⎡ ⎛ V ×I
⎞⎤
OUT
OUT
Efficiency Loss = ⎢-1 ⎜
⎟⎥ × 100
⎣ ⎝ VOUT × IOUT × PL ⎠⎦
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.
Compensation
The MIC2203 is an internally compensated, voltage
mode buck regulator. Voltage mode is achieved by
creating an internal 1MHz ramp signal and using the
output of the error amplifier to pulse width modulate
the switch node, maintaining output voltage
regulation. With a typical gain bandwidth of 100kHz,
the MIC2203 is capable of extremely fast transient
responses.
The MIC2203 is designed to be stable with a 10µH
inductor and a 2.2µF ceramic (X5R) output
capacitor.
Feedback
The MIC2203 provides a feedback pin to adjust the
output voltage to the desired level. This pin connects
internally to an error amplifier. The error amplifier
then compares the voltage at the feedback to the
internal 0.5V reference voltage and adjusts the
output voltage to maintain regulation. To calculate
the resistor divider network for the desired output is
as follows:
R1
R2 =
⎛V
⎞
⎜ OUT −1⎟
⎝ VREF
⎠
Synchronization
SYNC_IN allows the user to change the frequency
from 1MHz up to 1.25MHz or down to 800KHz. This
allows the ability to control the fundamental
frequency and all the resultant harmonics.
Maintaining a predictable frequency creates the
ability to either shift the harmonics away from
sensitive carrier and IF frequency bands or to
accurately filter out specific harmonic frequencies.
The SYNC_OUT function pin allows for the ability to
be able to sync up multiple MIC2203s in a “daisychain”, connecting SYNC_OUT to SYNC_IN of the
other MIC2203. Synchronizing multiple MIC2203s
benefits much in the same way as syncing up one
MIC2203. All regulators will run at the same fundamental frequency, resulting in matched harmonic
frequencies, simplifying design for sensitive
communication equipment.
Where VREF is 0.5V and VOUT is the desired output
voltage. A 10kΩ or lower resistor value from the
output to the feedback is recommended. Larger
resistor values require an additional capacitor (feedforward) from the output to the feedback. The large
high side resistor value and the parasitic
capacitance on the feedback pin (~10pF) can cause
an additional pole in the loop. The additional pole
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MIC2203
Figure 1. Master-Slave Operation
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MIC2203
MIC2203 with 10µH Inductor and 2.2µF Output Capacitor
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December 2004
MIC2203
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MIC2203
MIC2203BMM Evaluation Board Schematic
Figure 2. MIC2203BMM Evaluation Board Schematic
Bill of Materials
Item
Part Number
Manufacturer
Description
C1
06036D105MAT
AVX
1µF Ceramic Capacitor X5R, 6.3V, Size 0603
GRM185R60J105KE21D
Murata
1µF Ceramic Capacitor X5R, 6.3V, Size 0603
0201ZD103MAT2
AVX
10nF Ceramic Capacitor 6.3V, Size 0201
C2
GRM033R10J103KA01D
Murata
10nF Ceramic Capacitor 6.3V, Size 0202
06036D225MAT
AVX
2.2µF Ceramic Capacitor X5R, 6.3V, Size 0603
GRM185R60J22SKE21D
Murata
2.2µF Ceramic Capacitor X5R, 6.3V, Size 0603
LQH32CN100M
Murata
10µH Inductor
CDRH2D14-10
Sumida
10µH Inductor
R1
CRCW04021002F
Vishay-Dale
10kΩ 1%, Size 0402
R2
CRCW04021781F
CRCW04022491F
CRCW04023831F
CRCW04024991F
CRCW04027151F
CRCW04021002F
NA
Vishay-Dale
Vishay-Dale
Vishay-Dale
Vishay-Dale
Vishay-Dale
Vishay-Dale
1.78kΩ 1%, Size 0402 For 3.3VOUT
2.49kΩ 1%, Size 0402 For 2.5VOUT
3.83kΩ 1%, Size 0402 For 1.8VOUT
4.99kΩ 1%, Size 0402 For 1.5VOUT
7.15kΩ 1%, Size 0402 For 1.2VOUT
10kΩ 1%, Size 0402 For 1VOUT
Open For 0.5VOUT
U1
MIC2203BMM
Micrel, Inc.
1MHz High Efficiency Synchronous Buck Regulator
C3
L1
Notes:
1.
2.
3.
4.
5.
AVX: www.avx.com
Murata: www.murata.com
Sumida: www.sumida.com
Vishay-Dale: www.vishay.com
Micrel, Inc: www.micrel.com
December 2004
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Micrel, Inc.
MIC2203
Package Information
10-Pin MSOP (MM)
10-Pin 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.
© 2004 Micrel, Incorporated.
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