MIC2267

Input Current Limiting

Synchronous Buck Regulator

USB Power Maximizer™

USB Power Maximizer is a trademark of Micrel, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (

January 2011

M9999-011711-A

General Description

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

junction operating range from –40

°C to +125°C.

Datasheets and support documentation can be found on

Features

• 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

• Junction temperature range: −40°C to +125°C

Applications

• USB power

• Wireless router cards

• General buck converter applications

_______________________________________________________________________________________________________

Typical Application

Efficiency vs.

Output Current

50

55

60

65

70

75

80

85

90

95

100

00.5

11.5

2

OUTPUT CURRENT (A)

MIC2267 USB Input Current Limiting Synchronous Buck Regulator