MIC2267 Datasheet, PDF (1/19 Pages) Micrel Semiconductor – Input Current Limiting Synchronous Buck Regulator

MIC2267
Input Current Limiting
Synchronous Buck Regulator
USB Power Maximizer™
General Description
Features
The MIC2267 is a USB Power Maximizer™ which
transfers the maximum power from the limited USB current
source by shaping the input current limit profile. It
incorporates a high efficiency, integrated synchronous step
down regulator. Internal 150mΩ switches and adjustable
operating frequency allows the MIC2267 to achieve
greater than 90% efficiency across a broad load range. It
replaces the USB current limit switch, 5V buck regulator
and minimizes capacitance for many USB applications.
The adjustable frequency control can be utilized to move
harmonics away from sensitive frequency bands.
The MIC2267 allows the input current limit profile to be
shaped for various applications. With a current mode
control with external compensation, the MIC2267 transient
response can be optimized over load and output
capacitance making it highly flexible for many applications.
Additional features include 1µA shutdown current, output
current limit and thermal shutdown protection. The
MIC2267 is available in a 12-pin 3mm x 3mm MLF^® with a
junction operating range from –40°C to +125°C.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
• Input voltage range: 3.0V to 5.5V
• Output voltage adjustable down to 1.0V
• Up to 96% efficiency at 500mA output
• Efficiency >90% across a broad load range
• Fast transient response
• Adjustable frequency from 400kHz to 1.5MHz
• Adjustable input current limiting 100mA to over 1A
• 100% maximum duty cycle
• Fully integrated MOSFET switches
• Micropower shutdown
• Thermal shutdown and output current limit protection
• 12-pin 3mm x 3mm MLF^®
• Junction temperature range: −40°C to +125°C
Applications
• USB power
• Wireless router cards
• General buck converter applications
_______________________________________________________________________________________________________
Typical Application
MIC2267 USB Input Current Limiting Synchronous Buck Regulator
100
95
90
85
80
75
70
65
60
55
50
0
Efficiency vs.
Output Current
V_IN = 4.2V
V_IN = 5.5V
V_OUT = 3.3V
0.5
1
1.5
2
OUTPUT CURRENT (A)
Efficiency 5V_IN to 3.3V_OUT
USB Power Maximizer is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
January 2011
M9999-011711-A