MIC28500 Datasheet, PDF (1/29 Pages) Micrel Semiconductor – 75V/4A Hyper Speed Control™ Synchronous DC-DC Buck Regulator

MIC28500
75V/4A Hyper Speed Control™
Synchronous DC-DC Buck Regulator
SuperSwitcher II™
General Description
Features
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: www.micrel.com.
• 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
100
90
80
70
60
50
40
30
20
10
0
Efficiency (VIN = 48V)
vs. Output Current
fSW = 250kHz
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.8V
1
2
3
4
5
6
OUTPUT CURRENT (A)
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 [phone] • fax + 1 [phone] • http://www.micrel.com
June 2011
M9999-060311-B