MICREL MIC2224YML

MIC2224
High Efficiency 2MHz PWM Buck Converter with
DAC Input and 40mΩ Bypass Switch
General Description
Features
The MIC2224 is a high efficiency 2MHz PWM synchronous
buck switching regulator optimized for powering 2.5G and
3G CDMA RF Power Amplifiers. The output voltage of
MIC2224 can be dynamically adjusted with an external
DAC to maximize PA efficiency versus required output
power. When the PA requires the highest power, the DAC
can be used to enable a low on-resistance, 40mΩ, bypass
switch that powers the PA directly from the battery.
The 2MHz PWM operation of MIC2224 allows the smallest
possible components. It also allows the device to easily
meet stringent W-CDMA VOUT response specifications.
The MIC2224 operates from a 2.7V to 5.5V input, making
it ideal for single cell Li-Ion applications. The device
features built-in power MOSFETs that can supply up to
600mA of output current in PWM mode, or over 1A in
bypass mode. The MIC2224 can operate with a maximum
duty cycle of 100% for use in low-dropout conditions.
The MIC2224 has a junction temperature range of
–40°C to +125°C and is available in a 10-pin 3mm x 3mm
MLF® package.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
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2.7V to 5.5V input voltage range
DAC-adjustable output voltage down to 0.3V
600mA output current in PWM mode
Internally protected 40mΩ bypass switch
Allows direct connection of battery to load
Over 95% efficient
Fully integrated MOSFET switches
Constant 2MHz PWM operation
Internal soft-start
1% line and load regulation
<1µA shutdown current
Under-voltage lockout
Thermal shutdown and current limit protection
–40°C to +125°C junction temperature range
Applications
• Cellular phones
• PDAs
Typical Application
GND
7
PGND
GND
10
X
3
3.0
2.4
AC
DAC
AGND
Bypass
Mode
3.6
C2
1µF
ENABLE
D
6
4.2
V
DAC
8, 9
VIN = 4.2V
1.8
1.2
=
4
VOUT
4.8
UT
C1
1µF
AVIN
5.4
VOUT
O
5
SW
VIN
1
L1
4.7µH
V
2, 3
MIC2224
VOUT (V)
VIN 2.6V to 5.5V
0.6
0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
VDAC (V)
2MHz PWM Converter with DAC Input
and 40mΩ Bypass Switch
MLF and MicroLeadFrame are registered trademarks or 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
September 2006
1
M9999-091106
Micrel, Inc.
MIC2224
Ordering Information(1)
Part Number
Output
Voltage
Junction
Temp. Range
Package
Lead Finish
MIC2224YML
Adj.
–40°C to +125°C
10-Pin 3mm x 3mm MLF®
Pb-Free
Pin Configuration
SW 1
10 PGND
VIN 2
9 VOUT
VIN 3
8 VOUT
EN 4
7 AGND
AVIN
5
EP
6 DAC
10-Pin MLF® (ML)
Pin Description
Pin Number
Pin Name
1
SW
Switch (Output): Internal power MOSFET output switches.
2, 3
VIN
Supply Voltage (Input): Requires bypass capacitor to GND.
4
EN
A low level EN will power down the device, reducing the quiescent current to under
5µA (typ 1µA).
5
AVIN
Supply Voltage (Input): Requires bypass capacitor to GND.
6
DAC
DAC Control Input. Provides control of output voltage. The output voltage is 3 X the
DAC voltage. (Ex. 0.5VDAC = 1.5VOUT). Bypass mode is enabled when the DAC
voltage exceeds 1.2V.
7
AGND
Signal Ground of chip.
8, 9
VOUT
Source of Internal P-Channel MOSFET and Feedback of internal PWM regulator.
10
PGND
Power Ground of chip.
EP
Exposed Pad
September 2006
Pin Function
Connect to ground.
2
M9999-091106
Micrel, Inc.
MIC2224
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN) ............................................... 0V to 6V
Output Switch Voltage (VSW). ...........................................6V
DAC Input Voltage (VDAC)............................ 0V to VIN +0.3V
Output Switch Current (ISW)...........................................2.5A
Logic Input Voltage (VEN) ............................ 0V to VIN +0.3V
Storage Temperature (Ts) .........................–65°C to +150°C
Supply voltage (VIN) ....................................... 2.7V to +5.5V
Output Voltage (VOUT). ........................................ 0V to 5.5V
DAC Input Voltage (VDAC).................................... 0.1V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Thermal Resistance
MLF®-10 (θJA) ....................................................60°C/W
Electrical Characteristics(4)
VIN = VEN = 3.6V; VDAC = 0.6V; L = 4.7µH; COUT = 1µF; TA = 25°C, bold values indicate –40°C< TJ < +125°C, unless noted.
Parameter
Condition
Min
Typ
Max
Units
5.5
V
360
450
µA
1
5
µA
2.7
Supply Voltage Range
Total Quiescent Current
VDAC = 0.6V VOUT = 2.4V (regulator on, not switching)
Shutdown Current
VEN = 0V (regulator off)
100
Maximum Duty Cycle
%
Regulation
1.8
1.854
V
3.0V ≤ VIN ≤ 4.5, ILOAD= 10mA
0.05
0.5
%/V
0mA < IOUT < 500mA
0.2
ISW = -100mA, High-Side Switch
ISW = 100mA , Low-Side Switch
0.55
0.6
0.75
0.85
Ω
Ω
0.65
0.85
1.6
A
1.8
2
2.2
MHz
0.5
0.9
1.3
V
Output Voltage
VDAC = 0.6V, ILOAD =0mA
Output Voltage Line Regulation
Output Voltage Load Regulation
1.746
%
Output
Switch On-Resistance
Current limit (Peak SW Current)
Oscillator
Frequency
Enable / UVLO
Enable Pin Threshold
Enable Pin Hysteresis
30
Enable Pin Input Current
EN high to 90% VOUT
Under-Voltage Lockout Threshold
(turn-on)
UVLO Hysteresis
mV
0.01
1
µA
25
50
µs
2.6
2.7
V
85
mV
DAC Input
DAC Input Current
Output Voltage/DAC Voltage
0.15
(internally set)
2
3
µA
V/V
Bypass Switch
1.176
Bypass Switch Threshold
Bypass Switch Hysteresis
1.2
1.224
35
V
mV
Bypass Transition Time
10
µs
Bypass Switch On-Resistance
40
mΩ
5
Bypass Switch Leakage
1
Bypass Over-Current Limit
Current Limit Retry Time
Current Limit Retry Duty Cycle
September 2006
3
1.4
2.5
µA
A
32
µs
12.5
%
M9999-091106
Micrel, Inc.
Parameter
MIC2224
Condition
Min
Typ
Max
Units
Over Temperature Shutdown
Shutdown Temperature
160
°C
Over Temperature Shutdown
Hysteresis
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.
September 2006
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MIC2224
Typical Characteristics
Efficiency 2.7VOUT
100
EFFICIENCY (%)
4.2VIN
80
75
75
70
0.1 0.2 0.3 0.4 0.5
OUTPUT CURRENT (A)
60
0
0.6
3.6VIN
4.2VIN
100
3VIN
90
80
70
65
60
0.1 0.2 0.3 0.4 0.5
OUTPUT CURRENT (A)
70
60
50
10
0
0
0.6
1.836
1.827
1.818
1.809
1.800
1.791
VOUT = 1.8V
1.782 VDAC = 0.6V
VIN = 3.6V
1.773
0 100 200 300 400 500 600
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.827
3.0
2.0
-40°C
25°C
1.5
1.0
0.1 0.2 0.3 0.4 0.5
OUTPUT CURRENT (A)
0.2 0.4 0.6 0.8 1.0 1.2 1.4
DAC VOLTAGE (V)
September 2006
80
70
60
40
0
0.6
Output Voltage
vs. Temperature
3.6VIN
4.2VIN
3.3
0.1 0.2 0.3 0.4 0.5
OUTPUT CURRENT (A)
0.6
VOUT/DAC
vs. Temperature
3.2
2.05
2.00
1.95
1.90
1.80
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
5
3.0
2.9
2.7
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Frequency
vs. Temperature
2.10
3.1
2.8
VDAC = 0.6V
1.85
0.5
90 3V
IN
50
1.746
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
FREQUENCY (MHz)
VOUT /DAC
4.2VIN
2.15
3.5
0
0
3.6VIN
1.773
1.764
1.755
2.20
0.6
100
1.791
1.782
4.0
0.1 0.2 0.3 0.4 0.5
OUTPUT CURRENT (A)
Efficiency 0.6VOUT
1.818
1.809
1.800
Output Voltage
vs. DAC Voltage
125°C
50
0
0.6
40
30
20
Load Regulation
2.5
65
60
55
Efficiency 0.9VOUT
EFFICIENCY (%)
85
80
75
EFFICIENCY (%)
3VIN
0.1 0.2 0.3 0.4 0.5
OUTPUT CURRENT (A)
3.6VIN
4.2VIN
75
70
65
100
95
90
4.5
4VIN
80
Efficiency 1.2VOUT
55
50
0
3.5VIN
85
EFFICIENCY (%)
70
0
90
3VIN
90
85
80
VOUT /DAC
EFFICIENCY (%)
85
3.6VIN
100
95
3VIN
95
EFFICIENCY (%)
3VIN
95
90
Efficiency 1.5VOUT
450
QUIESCENT CURRENT (µA)
100
Efficiency 1.8VOUT
Quiescent Current
vs. Temperature
400
350
300
250
200
150
100
50
VIN = 3.6V
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
M9999-091106
Micrel, Inc.
MIC2224
Typical Characteristics (cont.)
400
ENABLE THRESHOLD (V)
QUIESCENT CURRENT (µA)
450
Quiescent Current
vs. Temperature
350
300
250
200
150
100
50
0
2.7
3.26 3.82 4.38 4.94
SUPPLY VOLTAGE (V)
September 2006
5.5
1.5
1.4
Enable Threshold
vs. Supply Voltage
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
2.7
3.26 3.82 4.38 4.94
SUPPLY VOLTAGE (V)
6
5.5
M9999-091106
Micrel, Inc.
MIC2224
Functional Characteristics
Bypass Mode Transient
Bypass Mode Transient
0V
DAC Voltage
(500mV/div)
DAC Voltage
(500mV/div)
0V
0V
0V
Current Limit Transient (Bypass Mode)
Current Limit Transient (PWM Mode)
Output Voltage
(2V/div)
Time 10µs
Output Voltage
(2V/div)
Time 10µs
VIN = 3.6V
VDAC = 1.3V
L = 4.7µH
COUT = 1µF
0V
VIN = 3.6V
VDAC = 1.3V
L = 4.7µH
COUT = 1µF
Output Current
(500mA/div)
Output Current
(500mA/div)
0V
0mA
0mA
Time 2ms
Time 100µs
Enable Transient
Load Transient
VIN = 3.6V
VDAC = 0.6V
L = 4.7µH
COUT = 1µF
Output Voltage
(100mV/div)
Output Voltage
(1V/div)
VIN = 4.2V
L = 4.7µH
COUT = 1µF
Output Voltage
(2V/div)
Output Voltage
(2V/div)
VIN = 4.2V
L = 4.7µH
COUT = 1µF
VIN = 3.6V
VDAC = 0.6V
L = 4.7µH
COUT = 1µF
Enable Voltage
(1V/div)
Output Current
(100mA/div)
0V
0mA
0V
Time 10µs
September 2006
Time 10µs
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Micrel, Inc.
MIC2224
Functional Characteristics (cont.)
Output Voltage Transient
Output Voltage
(1V/div)
Output Voltage
(1V/div)
Output Voltage Transient
0V
DAC Voltage
(500mV/div)
DAC Voltage
(500mV/div)
0V
VIN = 3.6V
L = 4.7µH
COUT = 1µF
0V
VIN = 3.6V
L = 4.7µH
COUT = 1µF
0V
Time 10µs
Time 10µs
VIN = 3.6V
VDAC = 0.6V
IOUT = 600mA
L = 4.7µH
COUT = 1µF
Switch Voltage
(2V/div)
Output Voltage Ripple
AC Coupled
(10mV/div)
Switch Voltage - Output Ripple
Time 400nµs
September 2006
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M9999-091106
Micrel, Inc.
MIC2224
Functional Diagram
VIN
VOUT
1.2V
AVIN
SW
DRIVER
DAC
EN
80k
40k
AGND
PGND
MIC2224 Block Diagram
September 2006
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M9999-091106
Micrel, Inc.
MIC2224
VOUT
The VOUT pin connects the internal bypass drain and
the feedback signal to the output. The bypass applies
the input voltage through a low resistance (40mΩ
typical) P-Channel MOSFET switch. The feedback signal
provides the control path to set the output at 3X the DAC
voltage.
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, a 1µF
capacitor is recommended close to VIN and the power
ground (PGND) pin for bypassing.
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.
AVIN
Analog VIN (AVIN) provides power to the internal
reference and control section. 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.
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.
DAC
The DAC pin is the control pin that sets the output
voltage. The Output voltage is 3X the voltage set on the
DAC pin. When 1.2V or greater is applied to the DAC
pin, the MIC2224 enters bypass mode. In bypass mode,
the input supply is connected to the output through a
40mΩ P-Channel MOSFET.
AGND
Signal 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.
EN
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 and bypass switch are placed in a "tristated" condition, where both the high side P-channel
Mosfet and the low-side N-channel are in an off or nonconducting state. Do not drive the enable pin above the
supply voltage.
September 2006
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M9999-091106
Micrel, Inc.
MIC2224
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 1µF, 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.
Application Information
The MIC2224 is a 600mA PWM power supply that
utilizes a dynamically adjustable output voltage for
powering RF power amplifiers. By dynamically adjusting
the output power as necessary, battery life can be
dramatically improved in battery powered RF
applications. For instances where high power is
required, the MIC2224 also has a bypass mode. Bypass
mode is enabled by driving the DAC pin above 1.2V.
This bypasses the input supply directly to the output
through a highly efficient, short circuit protected, 40mΩ P
channel MOSFET.
Inductor Selection
The MIC2224 is designed for use with a 4.7µH inductor.
Proper selection should ensure the inductor can handle
the maximum average and peak currents required by the
load. 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 that the peak current will not saturate the
inductor. Peak inductor current can be calculated as
follows:
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 lose most of their
capacitance over temperature and are therefore not
recommended. A minimum 1µF is recommended close
to the VIN and PGND pins for high frequency filtering.
Smaller case size capacitors are recommended due to
their lower ESR and ESL.
Output Capacitor
The MIC2224 is optimized for a 1µF ceramic output
capacitor. The MIC2224 utilizes type III internal
compensation and utilizes internal high frequency zeros
to compensate for the double pole roll off of the LC filter.
For this reason, larger output capacitors can create
September 2006
IPK = IOUT
11
⎛
V
VOUT ⎜⎜1 − OUT
VIN
⎝
+
2× f ×L
⎞
⎟⎟
⎠
M9999-091106
Micrel, Inc.
MIC2224
Bill of Materials
VIN 2.7V to 5.5V
2, 3
5
C1
1µF
4
DAC
6
MIC2224
VIN
SW
AVIN
Item
C1, C2
L1
Part Number
06036D105MAT2
AVX
PGND
10
GND
Description
Qty.
1µF Ceramic Capacitor X5R, 6.3V 0603
2
4.7µH 3.2mm x 2.5mm x 1.55mm
1
(2)
C1608X5R0J105K
TDK
GRM185R60J105KE21D
Murata(3)
LQH32CN4R7M53K
Murata(3)
CDRH2D14-4R7
U1
(1)
C2
1µF
DAC
7
Manufacturer
VOUT
8, 9
ENABLE
AGND
GND
VOUT
1
L1
4.7µH
Sumida
(4)
(2)
GLF201208T4R7M*
TDK
MIC2224YML
Micrel
4.7µH Inductor 94mΩ 3.2mm x 3.2mm x 1.55mm
4.7µH Inductor 660mΩ
(5)
Micrel Data Sheet Title Here
1
Notes:
1. AVX Tel: 843-448-9411
2. TDK. Tel: 714-508-8800
3. Murata Tel: 949-916-4000
4. Sumida Tel: 408-982-9660
5. Micrel Semiconductor Tel: 408-944-0800
* For maximum load currents less than 200mA
September 2006
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M9999-091106
Micrel, Inc.
MIC2224
Package Information
®
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.
© 2005 Micrel, Incorporated.
September 2006
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M9999-091106