RT6218A/B
18V, 2A, ACOT
TM
Step-Down Converter in 8 Pin TSOT-23
General Description
The RT6218A/B is a simple, easy-to-use, 2A
synchronous step-down DC-DC converter with an input
supply voltage range of 4.5V to 18V. The device
integrates low R
DS(ON)
power MOSFETs to achieve
high efficiency in a SOT23 package and build-in
accurate reference voltage (0.765V by product
options).
The RT6218A/B adopts Advanced Constant On-Time
(ACOT
TM
) control architecture to provide an ultrafast
transient response with few external components and
to operate in nearly constant switching frequency over
the line, load, and output voltage range. The RT6218A
operates in automatic PSM that maintains high
efficiency during light load operation. RT6218B
operates in Forced PWM that helps meet tight voltage
regulation accuracy requirements.
The RT6218A/B senses both FETs current for a robust
over-current
protection. The
device features
cycle-by-cycle current limit protection and prevent the
device from the catastrophic damage in output short
circuit, over current or inductor saturation. The
RT6218A/B series offers programmable start-up by
connecting a capacitor at external SS pin. The device
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. The
RT6218A/B are offered in TSOT-23-8(FC) package.
Features
Input Supply Voltage Range : 4.5V to 18V
2A Converter With Built-in 120m/65m Low
R
DS(
ON)
Power FETs
Advanced Constant On-Time (ACOT
TM
) Control
for Ultrafast Transient Response
Fixed Switching Frequency : 650kHz (SOT23-8)
Optional for Operation Modes :
Automatically
(RT6218A)
Power
Saving
Mode
(PSM)
Forced PWM Mode (RT6218B)
Optimized for Low-ESR Ceramic Output
Capacitors
1.5%
High-Accuracy Feedback Reference
Voltage
Output Voltage Range : up to 6.5V
Externally Adjustable Soft-Start
Monotonic Start-Up for Pre-biased Outputs
Both HS/LS FETs Protection for Robust Over
Current Protection
Input Under-Voltage Lockout (UVLO)
Output Under-Voltage Protection (UVP) with
Hiccup Mode
Over-Temperature Protection (OTP) (Thermal
Shutdown)
Enable Control
Power Good Indication
RoHS Compliant and Halogen Free
Available in TSOT-23-8 Package
Applications
Marking Information
RT6218AHRGJ8F
25=DNN
RT6218BHRGJ8F
26=DNN
25= : Product Code
DNN : Date Code
Set-Top Boxes
LCD TVs
Home Networking Devices
Surveillance
General Purpose
26= : Product Code
DNN : Date Code
Copyright © 2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6218A/B-01
October
2018
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
