®
RT6255A/B
5A, 18V, 500kHz, ACOTTM Step-Down Converter
General Description
Features
Input Supply Voltage Range : 4.5V to 18V
The RT6255A/B is a high-efficiency, synchronous step-
down DC-DC converter that can deliver up to 5A output
current from a 4.5V to 18V input supply. The RT6255A/B
adopts Advanced Constant On-Time (ACOTTM) control
architecture to provide an ultrafast transient response with
few external components and to operate in nearly constant
switching frequency over line, load, and output voltage
ranges.
Output Current : 5A
Advanced Constant On-Time (ACOTTM) Control for
Ultrafast Transient Response
Steady Switching Frequency : 500kHz
Forced PWM Mode (RT6255B)
Pulse-Skipping Mode (PSM) at Light Load
(RT6255A)
Optimized for Low-ESR Ceramic Output Capacitors
Programmable Output Voltage : 0.6V to 5V
Internal 45mΩ Switch and 23mΩ Synchronous
Rectifier
The RT6255A/B features cycle-by-cycle current limit
protection against short-circuit outputs, and soft-start
function to prevent inrush current during start-up. It also
includes input under-voltage lockout, output under-voltage
protection, and over-temperature protection (thermal
shutdown) to provide safe and smooth operation in all
operating conditions.
Cycle-by-cycle Current Limit Protection
Internal Soft-Start (Typ 1.5ms) or Externally
Adjustable, Pre-biased Compatible Soft-Start (Only
for Option with SS Pin)
Power Good Indicator (90%) (Only for Option with
PGOOD Pin)
Ordering Information
( )
RT6255A/B
Output Under-Voltage Protection (UVP)
Over-Temperature Protection (OTP)
Input Under-Voltage Lockout (UVLO)
Available in TSOT-23-6 (FC) and TSOT-23-8 (FC)
Packages
Package Type
J6F : TSOT-23-6 (FC)
J8F : TSOT-23-8 (FC)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Pin8 Definition
Empty means PGOOD pin
S : SS pin
Applications
Set Top Box
Portable TV
Access Point Router
DSL Modem
LCD TV
UVP Option
H : Hiccup
PSM/PWM
A : PSM/PWM
B : Force-PWM
Note :
Richtek products are :
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.
Copyright 2017 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS6255A/B-02 March 2017
www.richtek.com
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