MIC4685 Datasheet, PDF (1/15 Pages) Micrel Semiconductor – 3A SPAK SuperSwitcher™ Buck Regulator

MIC4685
Micrel
MIC4685
3A SPAK SuperSwitcher™ Buck Regulator
Final
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-lead
SPAK package.
The thermal performance of the SPAK allows it to replace
TO-220s and TO-263s (D² PAKs) 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 protec-
tion, frequency-foldback short-circuit protection, and thermal
shutdown.
The MIC4685 is available in an 7-lead SPAK package with a
junction temperature range of –40°C to +125°C.
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
Ordering Information
Part Number
MIC4685BR
Voltage
Adj
Junction Temperature Range
–40°C to +125°C
Package
SPAK-07L
Typical Applications
V_IN
8V to 30V
C_IN
33µF
35V
MIC4685BR
2 _IN
BS ¹
5 _EN
SW ⁶
FB ³
GND
4, Tab
C_BS
0.33µF/50V
L1
39µH
D1
3A
40V
R1
3.01k
R2
6.49k
1.8V Output Converter
V_OUT
1.8V/3A
C_OUT
330µF
6.3V
V_IN
5V
±10%
C_IN
68µF
10V
D_BS
3A, 20V
MIC4685BR
2 _IN
BS ¹
5 _EN
SW ⁶
FB ³
GND
4, Tab
C_BS
0.33µF/50V
L1
39µH
D1
3A
20V
R1
3.01k
R2
1.78k
5V to 3.3V Converter
V_OUT
3.3V/2A
330µF
6.3V
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
September 2002
1
MIC4685