The Future of Analog IC Technology
High Efficiency, Fast Transient, 7A, 28V
Synchronous Step-down Converter
in a Tiny 3x4mm QFN Package
FEATURES
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Wide 4.5V to 28V Operating Input Range
7A Output Current
Internal 30mΩ High-Side, 12mΩ Low-Side
Power MOSFETs
Proprietary Switching Loss Reduction
Technique
1% Reference Voltage
Programmable Soft Start Time
Soft Shutdown
200kHz to 1MHz Switching Frequency
SCP, OCP, OVP, UVP Protection and
Thermal Shutdown
Output Adjustable from 0.8V to 13V
Available in a QFN20 (3x4mm) Package
Notebook Systems and I/O Power
Networking Systems
Optical Communication Systems
Distributed Power and POL Systems
NB638
DESCRIPTION
The NB638 is a fully integrated, high frequency
synchronous rectified step-down switch mode
converter. It offers a very compact solution to
achieve 7A continuous output current over a
wide input supply range with excellent load and
line regulation. The NB638 operates at high
efficiency over a wide output current load range.
Constant-On-Time
(COT)
control
mode
provides fast transient response and eases loop
stabilization.
Full protection features include SCP, OCP, OVP,
UVP and thermal shutdown.
The NB638 requires a minimum number of
readily available standard external components
and is available in a space-saving QFN20
(3x4mm) package.
APPLICATIONS
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Products, Quality Assurance page.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
VIN
8,19
IN
BST
7
R7
C
IN
C3
NB638
FREQ
20
VCC
2
SW
9,10,17,18
VOUT 1.05V
R4
C4
R1
C2
6
PGOOD
EN
FB
3
EN
5
R2
SS AGND PGND
4
C
SS
33nF
1
11-16
NB638 Rev.1.16
4/18/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
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MPS [ MONOLITHIC POWER SYSTEMS ]
