MIC4685_10 Datasheet, PDF (1/17 Pages) Micrel Semiconductor – 3A SPAK SuperSwitcher Buck Regulator

MIC4685
3A SPAK SuperSwitcher™
Buck Regulator
General Description
The MIC4685 is a high-efficiency 200kHz stepdown (buck)
switching regulator. Power conversion efficiency of above
85% is easily obtainable for a wide variety of applications.
The MIC4685 achieves 3A of continuous current in the
7-pin SPAK package.
The thermal performance of the SPAK allows it to replace
TO-220s and TO-263s (D²PAKs) in many applications.
The SPAK saves board space with a 36% smaller footprint
than TO-263.
High-efficiency is maintained over a wide output current
range by utilizing a boost capacitor to increase the voltage
available to saturate the internal power switch. As a result
of this high-efficiency, only the ground plane of the PCB is
needed for a heat sink.
The MIC4685 allows for a high degree of safety. It has a
wide input voltage range of 4V to 30V (34V transient),
allowing it to be used in applications where input voltage
transients may be present. Built-in safety features include
over-current protection, frequency-foldback short-circuit
protection, and thermal shutdown.
The MIC4685 is available in a 7-pin SPAK package with a
junction temperature range of –40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• Low 2mm profile SPAK package
• 3A continuous output current
• Wide 4V to 30V input voltage range (34V transient)
• Fixed 200kHz PWM operation
• Over 85% efficiency
• Output voltage adjustable to 1.235V
• All surface mount solution
• Internally compensated with fast transient response
• Over-current protection
• Frequency foldback short-circuit protection
• Thermal shutdown
Applications
• Point-of-load power supplies
• Simple high-efficiency step-down regulators
• 5V to 3.3V/2A conversion
• 12V to 5V/3.3V/2.5V/1.8V 3A conversion
• Dual-output ±5V conversion
• Base stations
• LCD power supplies
• Battery chargers
___________________________________________________________________________________________________________
Typical Application
V_IN
8V to 30V
C_IN
33µF
35V
MIC4685_R
2 _IN
BS ¹
5 _EN
SW ⁶
FB ³
GND
4, Tab
C_BS
0.33µF/50V
L1
39mH
D1
3A
40V
R1
3.01k
R2
6.49k
1.8V Output Converter
V_OUT
1.8V/3A
C_OUT
330µF
6.3V
SuperSwitcher 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 2010
1
M9999-012610