®
RT6251A/B
3A, 18V, Synchronous Step-Down Converter
General Description
The RT6251A/B is a high efficiency, monolithic
synchronous step-down DC/DC converter that can deliver
up to 3A output current from a 4.5V to 18V input supply.
The RT6251A/B current-mode architecture with external
compensation allows the transient response to be
optimized over a wide range of loads and output capacitors.
Cycle-by-cycle current limit provides protection against
shorted outputs and soft-start eliminates input current
surge during start-up. Fault condition protections include
output under-voltage protection, output over-voltage
protection, and over-temperature protection. The low
current shutdown mode provides output disconnection,
enabling easy power management in battery-powered
systems.
Features
Ω
Ω
Low R
DS(ON)
Power MOSFET Switches 46mΩ/36mΩ
Input Voltage Range : 4.5V to 18V
Adjustable Switching Frequency : 200kHz to 1.2MHz
Current-Mode Control
Synchronous to External Clock : 200kHz to 1.2MHz
Accurate Voltage Reference 0.8V
±
1%
Monotonic Start-Up into Pre-biased Outputs
Adjustable Soft-Start
Power Good Indicator
Under-Voltage and Over-Voltage Protection
Input Under-Voltage Lockout
Ordering Information
RT6251A/B
Package Type
QW : WQFN-14AL 3.5x3.5 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
H : Hiccup UVP
N : Non-UVP
A : PSM
B : PWM
Note :
Richtek products are :
�½
Applications
High Performance Point of Load Regulation
Notebook Computers
High Density and Distributed Power Systems
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
�½
Simplified Application Circuit
V
IN
C
IN
RT6251A/B
BOOT
VIN
C
BOOT
PVIN
Enable
PGOOD
R
OSC
C
SS
SS/TR
GND
EN
PGOOD
RT/SYNC
FB
COMP
R
COMP1
C
COMP2
C
COMP1
R2
LX
L
R1
C
OUT
V
OUT
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6251A/B-00 November 2015
www.richtek.com
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RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
