Features
 3A Converter With Built-in 85mΩ/40mΩ Low RDS(ON)
Power FETs
 Input Supply Voltage Range : 4.5V to 24V
 Output Voltage Range : 0.791V to 6V
 Advanced Constant On-Time (ACOTTM) Control
 Ultrafast Transient Response
 No Needs For External Compensations
 Optimized for Low-ESR Ceramic Output Capacitors
 0.791V ±1.5% High-Accuracy Feedback Reference
Voltage
 Low Quiescent Current (150μA typ.)
 Both HS/LS FETs Protection for Robust Over-Current
Protection
 Optional for Operation Modes :
 Power Saving Mode (PSM) at Light Load (RT6217A)
 Forced PWM Mode (RT6217B)
 Light-load VOUT Ripple Reduction Technology in
PSM
 Fixed Switching Frequency : 500kHz
 Externally Adjustable Soft-Start
 Monotonic Start-up for Pre-biased Output
 Input Under-Voltage Lockout (UVLO)
 Output Under-Voltage Protection (UVP) with Hiccup
Mode
 Power Good Indication
 Enable Control
 Available In TSOT-23-8 (FC) Package

General Description
The RT6217A/B is a simple, easy-to-use, 3A synchronous
step-down DC-DC converter with an input supply voltage
range of 4.5V to 24V. The device build-in an accurate
0.791V reference voltage and integrates low RDS(ON) power
MOSFETs to achieve high efficiency in a TSOT-23-8 (FC)
package.
The RT6217A/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 the
line, load, and output voltage range. The RT6217A operates
in automatic PSM that maintains high efficiency during
light load operation. The RT6217B operates in Forced
PWM that helps meet tight voltage regulation accuracy
requirements.
The RT6217A/B senses both FETs current for a robust
over-current protection. It features cycle-by-cycle current
limit protection and prevent the device from the catastrophic
damage in output short circuit, over current or inductor
saturation. An externally adjustable soft-start function
prevents inrush current during start-up. 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 RT6217A/B is offered in a TSOT-
23-8(FC) package.