MIC2224_06 Datasheet, PDF (1/13 Pages) Micrel Semiconductor – High Efficiency 2MHz PWM Buck Converter with DAC Input and 40mΩ Bypass Switch

MIC2224
High Efficiency 2MHz PWM Buck Converter with
DAC Input and 40mΩ Bypass Switch
General Description
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 V_OUT 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.
Features
• 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
V_IN 2.6V to 5.5V
C1
1µF
DAC
L1
MIC2224
4.7µH
2, 3
VIN
1
SW
5
AVIN
8, 9
VOUT
4
ENABLE
C2
1µF
6
DAC
GND
AGND PGND
7
10
V_OUT
GND
2MHz PWM Converter with DAC Input
and 40mΩ Bypass Switch
5.4
4.8 ^{VIN = 4.2V}
4.2
3.6
3.0
3
X
2.4
1.8
1.2
= ^{V DAC}
V ^OUT
Bypass
Mode
0.6
00 _{0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8}
V_DAC (V)
MLF and MicroLeadFrame are registered trademarks or Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
September 2006
1
M9999-091106