MIC2224 Datasheet, PDF (1/13 Pages) Micrel Semiconductor – High Efficiency 2MHz PWM Buck Converter with DAC Input and 40mOHM Bypass Switch

MIC2224
High Efficiency 2MHz PWM Buck
Converter with DAC Input and 40mΩ
Bypass Switch
Preliminary
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 3mm x 3mm
MLF^TM-10L package.
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
Micrel, Inc. • 2180 Fortune Drive • San Jose, Ca 95131 • USA • tel [phone] • fax [phone] • http://www.micrel.com
2005January 2005
M9999-012705
[e-mail]