18V, 2A, ACOT^TM Step-Down Converter in 8 Pin TSOT-23

RT6218A/RT6218B

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 RDS(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.

Applications

Set-Top Boxes
LCD TVs
Home Networking Devices
Surveillance
General Purpose

Key Spec.

	RT6218A	RT6218B
Status	Active	Active
Vin (min) (V)	4.5	4.5
Vin (max) (V)	18	18
Number of Outputs	1	1
Vout (min) (V)	0.765	0.765
Vout (max) (V)	6.5	6.5
Output Adj. Method	Resistor	Resistor
Iout (max) (A)	2	2
Current Limit (typ) (A)	3.2	3.2
Freq (typ) (kHz)	650	650
Ext Sync	No	No
Ron_HS (typ) (mOhm)	120	120
Ron_LS (typ) (mOhm)	65	65
Iq (typ) (mA)	0.5	0.5
Features	ACOT Control;Adjustable Soft-Start;COT Control;Cycle-by-Cycle Current Limit;Enable Input;Internal Compensation;OCP;OTP;PSM;Power Good;UVP	ACOT Control;Adjustable Soft-Start;COT Control;Cycle-by-Cycle Current Limit;Enable Input;Internal Compensation;OCP;OTP;Power Good;UVP
Package Type	TSOT-28(FC)	TSOT-28(FC)

Features

Input Supply Voltage Range : 4.5V to 18V
2A Converter With Built-in 120mΩ/65mΩ 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 Power Saving Mode (PSM) (RT6218A)
► 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