MIC2205_06 Datasheet, PDF (1/16 Pages) Micrel Semiconductor – 2MHz PWM Synchronous Buck Regulator with LDO Standby Mode

MIC2205
2MHz PWM Synchronous Buck
Regulator with LDO Standby Mode
General Description
The Micrel MIC2205 is a high efficiency 2MHz PWM
synchronous buck (step-down) regulator that
features a LOWQ™ LDO standby mode that draws
only 18µA of quiescent current. The MIC2205
allows an ultra-low noise, small size, and high
efficiency solution for portable power applications.
In PWM mode, the MIC2205 operates with a
constant frequency 2MHz PWM control. Under light
load conditions, such as in system sleep or standby
modes, the PWM switching operation can be
disabled to reduce switching losses. In this light
load LOWQ™ mode, the LDO maintains the output
voltage and draws only 18µA of quiescent current.
The LDO mode of operation saves battery life while
not introducing spurious noise and high ripple as
experienced with pulse skipping or bursting mode
regulators.
The MIC2205 operates from 2.7V to 5.5V input and
features internal power MOSFETs that can supply
up to 600mA output current in PWM mode. It can
operate with a maximum duty cycle of 100% for use
in low-dropout conditions.
The MIC2205 is available in the 3mm x 3mm MLF-
10L package with a junction operating range from
–40°C to +125°C.
Data sheets and support documentation can be
found on Micrel’s web site at www.micrel.com.
Features
• 2.7 to 5.5V supply voltage
• Light load LOWQ™ LDO mode
18µA quiescent current
Low noise, 75µVrms
• 2MHz PWM mode
Output current to 600mA
>95% efficiency
100% maximum duty cycle
• Adjustable output voltage option down to 1V
Fixed output voltage options available
• Ultra-fast transient response
• Stable with 1µF ceramic output capacitor
• Fully integrated MOSFET switches
• Micropower shutdown
• Thermal shutdown and current limit protection
• Pb-free 3mm x 3mm MLF-10L package
• –40°C to +125°C junction temperature range
Applications
• Cellular phones
• PDAs
• USB peripherals
____________________________________________________________________________________________________
Typical Application
V_IN
2.7V to 5.5V
C1
1µF
LowQ
C2
0.1µF
MIC2205
8 _VIN
4 _AVIN
SW ⁹
LDO ²
6 _EN
7 _LOWQ
3 _BIAS
FB ⁵
2.2µH
R1
100k
R2
125k
C3
100pF
V_OUT
C4
2.2µF
GND
PGND AGND
10
1
GND
Adjustable Output Buck Regulator with LOWQ™ Mode
LOWQ is a trademark of Micrel, Inc
Micrel, Inc • 2180 Fortune Drive • San Jose, Ca 95131 • USA • tel [phone] • fax [phone] • http://www.micrel.com
March 2005
M9999-031105
www.micrel.com