MIC26903 Datasheet, PDF (1/31 Pages) Micrel Semiconductor – 28V, 9A Hyper Light Load Synchronous DC/DC Buck Regulator

MIC26903
28V, 9A Hyper Light Load™
Synchronous DC/DC Buck Regulator
SuperSwitcher IIG™
General Description
Features
The Micrel MIC26903 is a constant-frequency,
synchronous DC/DC buck regulator featuring adaptive on-
time control architecture. The MIC26903 operates over a
supply range of 4.5V to 28V. It has an internal linear
regulator which provides a regulated 5V to power the
internal control circuitry. MIC26903 operates at a constant
600kHz switching frequency in continuous conduction
mode and can be used to provide up to 9A of output
current. The output voltage is adjustable down to 0.8V.
Micrel’s Hyper Light Load™ architecture provides the same
high-efficiency and ultra-fast transient response as the
Hyper Speed Control™ architecture under medium to heavy
loads, but also maintains high efficiency under light load
conditions by transitioning to variable frequency,
discontinuous mode operation.
The MIC26903 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, thermal shutdown, internal
soft-start to reduce the inrush current, foldback current
limit and “hiccup mode” short-circuit protection. The
MIC26903 includes a Power Good (PG) output to allow
simple sequencing.
All support documentation can be found on Micrel’s web
site at: www.micrel.com.
• Hyper Light Load™ efficiency – up to 80% at 10mA
• Hyper Speed Control™ architecture enables
− High delta V operation (V_IN = 28V and V_OUT = 0.8V)
− Small output capacitance
• Input voltage range: 4.5V to 28V
• Output current up to 9A
• Up to 95% efficiency
• Adjustable output voltage from 0.8V to 5.5V
• ±1% FB accuracy
• Any Capacitor^TM stable − zero-to-high ESR
• 600kHz switching frequency
• Power Good (PG) output
• Foldback current-limit and “hiccup” mode short-circuit
protection
• Safe start-up into pre-biased loads
• 5mm × 6mm MLF^® package
• –40°C to +125°C junction temperature range
Applications
• Distributed power systems
• Telecom/networking infrastructure
• Printers, scanners, graphic cards and video cards
___________________________________________________________________________________________________________
Typical Application
100
95
90
85
80
75
70
65
60
55
50
0
Efficiency (V_IN = 12V)
vs. Output Current
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.9V
0.8V
V_IN = 12V
3
6
9
12
OUTPUT CURRENT (A)
Hyper Speed Control, Hyper Light Load, 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
July 2011
M9999-071311-A