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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
Preset Vout (V)
Output Adj. Method Resistor
Iout (max) (A) 12
Current Limit (typ) (A) 16
Freq (typ) (kHz) 500
Freq (min) (kHz)
Freq (max) (kHz)
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?2017/03/30 522
Reference Design
TitleLast UpdateShareDownload
Richtek Load Transient Tool2018/11/01
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