MIC2224
High Efficiency 2MHz PWM Buck Converter with
DAC Input and 40m Bypass Switch
General Description Features
The MIC2224 is a high efficiency 2MHz PWM synchronous 2.7V to 5.5V input voltage range
buck switching regulator optimized for powering 2.5G and
DAC-adjustable output voltage down to 0.3V
3G CDMA RF Power Amplifiers. The output voltage of
600mA output current in PWM mode
MIC2224 can be dynamically adjusted with an external
Internally protected 40m bypass switch
DAC to maximize PA efficiency versus required output
power. When the PA requires the highest power, the DAC Allows direct connection of battery to load
can be used to enable a low on-resistance, 40m , bypass
Over 95% efficient
switch that powers the PA directly from the battery.
Fully integrated MOSFET switches
The 2MHz PWM operation of MIC2224 allows the smallest
Constant 2MHz PWM operation
possible components. It also allows the device to easily
Internal soft-start
meet stringent W-CDMA V response specifications.
OUT
1% line and load regulation
The MIC2224 operates from a 2.7V to 5.5V input, making
<1A shutdown current
it ideal for single cell Li-Ion applications. The device
features built-in power MOSFETs that can supply up to
Under-voltage lockout
600mA of output current in PWM mode, or over 1A in
Thermal shutdown and current limit protection
bypass mode. The MIC2224 can operate with a maximum
40C to +125C junction temperature range
duty cycle of 100% for use in low-dropout conditions.
The MIC2224 has a junction temperature range of
Applications
40C to +125C and is available in a 10-pin 3mm x 3mm
Cellular phones
MLF package.
PDAs
Data sheets and support documentation can be found on
Micrels web site at www.micrel.com.
Typical Application
L1
MIC2224 4.7H 5.4
V 2.6V to 5.5V V
IN 2, 3 1 OUT V =4.2V
IN
4.8
VIN SW
5 8, 9
4.2
AVIN VOUT
Bypass
3.6
4
Mode
C1 C2
ENABLE
1F 1F
3.0
6
DAC
DAC
2.4
1.8
AGND PGND
1.2
710
GND GND
0.6
0
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
2MHz PWM Converter with DAC Input
V (V)
DAC
and 40m 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 Micrel, Inc. MIC2224
(1)
Ordering Information
Part Number Output Junction Package Lead Finish
Voltage Temp. Range
MIC2224YML Adj. 40C to +125C 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
AVIN56EP DAC
10-Pin MLF (ML)
Pin Description
Pin Number Pin Name Pin Function
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
5A (typ 1A).
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 = 1.5V ). Bypass mode is enabled when the DAC
OUT
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 Connect to ground.
M9999-091106
September 2006 2