®
RT6257A/B
18V, 6A, 500kHz, ACOT
TM
Step-Down Converter in 6 pin
TSOT-23
General Description
The RT6257A/B is a high-performance, synchronous step-
down DC-DC converter that can deliver up to 6A output
current from a 4.5V to 18V input supply. The device
integrates low R
DS(ON)
power MOSFETs, accurate 0.6V
reference and an integrated diode of bootstrap circuit to
offer a very compact solution.
The RT6257A/B adopts Advanced Constant On-Time
(ACOT
TM
) control architecture that provides ultrafast
transient response and further reduces the external-
component count. In steady states, the ACOT
TM
operates
in nearly constant switching frequency over line, load and
output voltage ranges and makes the EMI filter design
easier.
The device offers Independent enable control input pin for
easily sequence control. To control the inrush current
during the startup, the device provides a fixed 1.5ms soft-
start up. Fully protection features are also integrated in
the device including the cycle-by-cycle current limit
control, UVP, input UVLO and OTP.
The RT6257A/B is available in the TSOT-23-6 (FC) package.
Features
4.5V to 18V Input Voltage Range
6A Output Current
Constant-On-Time Mode to Enables Fast Transient
Response
Low Output Ripple and Allows Ceramic Output
Capacitor
500kHz Switching Frequency
High Efficient Internal Power MOSFET Switch
Optimized for Lower Duty Cycle Applications
Integrated 30mΩ/20mΩ MOSFETs
Ω
Ω
Adjustable Output Voltage from 0.6V to 5V
Internal Soft-Start (1.5ms typ.)
Built-In UVP/OTP
Input Under Voltage Lockout
TSOT23-6 (FC) Package
Applications
Ordering Information
RT6257A/B
Package Type
J6F : TSOT-23-6 (FC)
Lead Plating System
G : Green (Halogen Free and Pb Free)
UVP Option
H : Hiccup
PSM/PWM
A : PSM/PWM
B : Force-PWM
Note :
Richtek products are :
�½
Set Top Box
Portable TV
Access Point Router
DSL Modem
LCD TV
Pin Configuration
(TOP VIEW)
BOOT LX
6
5
2
VIN
4
3
FB
EN GND
TSOT-23-6 (FC)
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.
is a registered trademark of Richtek Technology Corporation.
�½
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
DS6257A/B-03 October
2018
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
