NB679A
28V, Low IQ, Fixed 5.1V, 8A,
Synchronous Buck Converter
with 100mA LDO and LP# VOUT Scaling
DESCRIPTION
The NB679A is a fully integrated, high-
frequency, synchronous, rectified, step-down,
switch-mode converter with a fixed 5.1V output
and low-power mode voltage scaling. It offers a
very compact solution to achieve an 8A
continuous output current and a 10A peak
output current over a wide input supply range
with excellent load and line regulation.
The NB679A operates at high efficiency over a
wide output current load range based on MPS
proprietary switching loss reduction technology
and internal low Ron power MOSFETs.
Adaptive constant-on-time (COT) control mode
provides fast transient response and eases loop
stabilization. The DC auto-tune loop provides
good load and line regulation.
The NB679A provides a fixed 5V LDO, which
can be used to power the external peripheries.
Full protection features include OC limit, OVP,
UVP, and thermal shutdown.
The converter requires a minimum number of
external components and is available in a
QFN-12 2mm x 3mm package.
FEATURES
Wide 5.5V to 28V Operating Input Range
Fixed 5.1V Vout (+2% of 5V Vout)
LP# Output Voltage Scaling (-3% of 5V Vout)
Supports Large Duty Operation
Ultrasonic Mode
100μA Low Quiescent Current
8A Continuous Output Current and 10A
Peak Output Current
Adaptive COT for Fast Transient
DC Auto-Tune Loop
Stable with POSCAP and Ceramic Output
Capacitors
Built-In 5V, 100mA LDO with Switch Over
1% Reference Voltage
Internal Soft Start
Output Discharge
700kHZ Switching Frequency
OCP, OVP, UVP, and Thermal Shutdown
Latch-Off Reset via EN or Power Cycle
QFN-12 2mm x 3mm Package
APPLICATIONS
Laptop Computers
Tablet PCs
Networking Systems
Flat Panel Televisions and Monitors
Distributed Power Systems
All MPS parts are lead-free, halogen-free, and adhere to the RoHS directive. For
MPS green status, please visit the MPS website under Quality Assurance.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
VIN
5.5V-24V
22μF
LP#
GND EN
5V/ 100mA
4.7μF
3.3Ω
VIN
BST
SW
LP#
NB679A VOUT
EN
PGND
LDO
PG
AGND
VCC
100kΩ
220nF
1.5μH
GND
1μF
VOUT
5.1V/8A
88μF
NB679A Rev. 1.03
www.MonolithicPower.com
1
7/27/2017
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2017 MPS. All Rights Reserved.
