RT7241A

12A, 23V, 500kHz, ACOT® Synchronous Buck Converter with VTT LDO for Memory Power Supply

The RT7241A provides a complete power supply for DDR3/DDR3L/LPDDR3/DDR4 memory systems. It integrates an Advanced Constant On-Time (ACOT®) mode synchronous Buck converter with a 1.5A sink/source tracking linear regulator.

The PWM converter provides low quiescent supply current, high efficiency, excellent transient response, and high DC output accuracy needed for stepping down high-voltage batteries to generate low-voltage chipset RAM supplies in notebook computers. The ACOT® control scheme handles wide input/output voltage ratios with ease and provides a very fast response to load transients with no external compensators.

The 1.5A sink/source VTT LDO maintains fast transient response only requiring 10μF ceramic output capacitance. The RT7241A supports all of the sleep state controls placing VTT at high-Z in S3 and discharging VDDQ and VTT in S4/S5.

The RT7241A provides complete protection features including OCP, OVP, UVP, and thermal shutdown. The RT7241A is available in the UQFN-18L 3x4 package.

Applications

DDR3/DDR3L/LPDDR3/DDR4 Memory Power Supplies
Notebook computers

Key Spec.
	RT7241A
Status	Active
Vin (min) (V)	4.5
Vin (max) (V)	23
Number of Outputs	1
Vout (min) (V)	0.6
Vout (max) (V)	1.5
Output Adj. Method	Resistor
Iout (max) (A)	12
Current Limit (typ) (A)	16
Freq (typ) (kHz)	500
Ext Sync	No
Ron_HS (typ) (mOhm)	17
Ron_LS (typ) (mOhm)	4.5
Iq (typ) (mA)	0.1
Features	ACOT Control;Adjustable Current Limit;Built-in Bootstrap Switch;COT Control;Cycle-by-Cycle Current Limit;Diode Emulation Mode;Enable Input;Fast Transient Response;Internal Compensation;OCP;OTP;OVP;Power Good;SCP;Stable with Ceramic Capacitor;UVP
Package Type	UQFN3x4-18(FC)

Features

DDR3/DDR3L/LPDDR3/DDR4 Complete Solution
PWM Converter (VDDQ)
► 100μA Low Quiescent Supply Current at S3 Mode
► ACOT^TM Mode Performs Fast Transient Response
► Support MLCC Output Capacitors
► Integrated Low On-Resistance MOSFETs
17mΩ of High-Side MOSFET
4.5mΩ of Low-Side MOSFET
► Adjustable from 0.6V to 1.5V Output Range for 1.5V (DDR3), 1.35V (DDR3L), 1.2V (LPDDR3) and 1.2V (DDR4)
► 4.5V to 23V Battery Input Range
► 500kHz Switching Frequency
► Resistor Adjustable Valley Current Limit
► Over-/Under-Voltage Protection
► Internal Voltage Ramp Soft-Start
► Power Good Indicator
1.5A LDO (VTT)
► Capable to Sink and Source up to 1.5A
► LDO Input Available to Optimize Power Losses
► Require Only 10μF Ceramic Output Capacitor
► Integrated Divider Tracks 1/2 VDDQ for VTT
► Accuracy ±20mV for VTT
► Support High-Z in S3 and Soft-Off in S4/S5
Tracking Mode Discharge Control
Thermal Capable Flip-chip (FC) Package for 12A VDDQ Converter and 1.5A VTT LDO
RoHS Compliant and Halogen Free

Datasheet
Title	Version	Last Update	Download
RT7241A: 12A, 23V, 500kHz, ACOT® Synchronous Buck Converter with VTT LDO for Memory Power Supply	V2.0	2017/02/02

Technical Documents
Title	Item Type	Last Update
The Calculation of Output DC Offset for ACOT™ Control Buck Converter with Feed-forward Compensator	App. Note	2015/12/03
ACOT™ (Advanced Constant-On Time) Synchronous Step-Down Converters [Oct., 2015]	Selection Guide	2015/10/02
Buck Converter Selection Criteria	App. Note	2015/05/01
Comparing Buck Converter Topologies	App. Note	2015/01/01
ACOT^® Stability Testing	App. Note	2013/11/01

Videos
Title	Last Update	Views
How to estimate control loop bandwidth from the transient response time?	2017/03/30	2670

Reference Design
Title	Last Update	Download
Richtek Load Transient Tool	2022/07/25

Please confirm with our distributor or sales representative for actual stock status.