MIC28500
75V/4A Hyper Speed Control™
Synchronous DC-DC Buck Regulator
SuperSwitcher II™
General Description
The Micrel MIC28500 is an adjustable frequency,
synchronous buck regulator featuring a unique adaptive on-
time control architecture. The MIC28500 operates over an
input supply range of 30V to 75V and provides a regulated
output of up to 4A of output current. The output voltage is
adjustable down to 0.8V with a guaranteed accuracy of ±1%.
Micrel’s Hyper Speed Control™ architecture allows for ultra-
fast transient response while reducing the output capacitance
and also makes (High V
IN
)/(Low V
OUT
) operation possible.
This adaptive t
ON
ripple control architecture combines the
advantages of fixed-frequency operation and fast transient
response in a single device.
The MIC28500 offers a full suite of protection features to
ensure protection of the IC during fault conditions. These
include undervoltage lockout to ensure proper operation
under power-sag conditions, internal soft-start to reduce
inrush current, foldback current limit, “hiccup” mode short-
circuit protection and thermal shutdown.
All support documentation can be found on Micrel’s web
site at:
Features
•
Hyper Speed Control™ architecture enables
-High
Delta V operation (V
IN
= 75V and V
OUT
= 0.8V)
-Small
output capacitance
30V to 75V voltage input
Adjustable output down to 0.8V
±1% FB accuracy
Any Capacitor™ Stable
-
Zero-ESR to high-ESR output capacitors
4A output current capability, up to 90% efficiency
100kHz to 500kHz switching frequency
Internal compensation
Foldback current-limit and “hiccup” mode short-circuit
protection
Thermal shutdown
Supports safe startup into a pre-biased load
–40°C to +125°C junction temperature range
28-pin 5mm
×
6mm MLF
®
package
•
•
•
•
•
•
•
•
•
•
•
•
Applications
•
Distributed power systems
•
Communications/networking infrastructure
•
Set-top box, gateways and routers
•
Printers, scanners, graphic cards and video cards
___________________________________________________________________________________________________________
Typical Application
Efficiency (V
IN
= 48V)
vs. Output Current
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
1
2
3
4
5
6
OUTPUT CURRENT (A)
f
SW
= 250kHz
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.8V
Hyper Speed Control, SuperSwitcher II and Any Capacitor are trademarks of Micrel, Inc.
MLF and
MicroLeadFrame
are registered trademarks of Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
June 2011
M9999-060311-B