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

RT7241A

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The RT7241A provides a complete power supply for DDR3/DDR3L/LPDDR3/DDR4 memory systems. It integrates an Advanced Constant On-Time (ACOTTM) 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 ACOTTM 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;Cycle-by-Cycle Current Limit;Diode Emulation Mode;Enable Input;Fast Transient Response;OCP;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
    ► ACOTTM 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
TitleLast UpdateShareDownload
12A, 23V, 500kHz, ACOT™ Synchronous Buck Converter with VTT LDO for Memory Power Supply2016/01/15
Technical Documents
TitleLast UpdateShareDownload
ACOT™ Stability Testing2019/03/18
ACOT™ (Advanced Constant-On Time) Synchronous Step-Down Converters2018/11/15
Comparing Buck Converter Topologies2018/09/20
Buck Converter Selection Criteria2016/08/04
The Calculation of Output DC Offset for ACOT™ Control Buck Converter with Feed-forward Compensator2016/07/07
Videos
TitleLast UpdateShareViews
How to estimate control loop bandwidth from the transient response time?2017/03/30 586
Reference Design
TitleLast UpdateShareDownload
Richtek Load Transient Tool2019/01/09
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