®
RT7241A
12A, 23V, 500kHz, ACOT
TM
Synchronous Buck Converter
with VTT LDO for Memory Power Supply
General Description
The RT7241A provides a complete power supply for DDR3/
DDR3L/LPDDR3/DDR4 memory systems. It integrates an
Advanced Constant On-Time (ACOT
TM
) 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
TM
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.
Features
DDR3/DDR3L/LPDDR3/DDR4 Complete Solution
PWM Converter (VDDQ)
�½
100μA Low Quiescent Supply Current at S3 Mode
μ
TM
�½
ACOT
�½
Mode Performs Fast Transient Response
Support MLCC Output Capacitors
�½
Integrated Low On-Resistance MOSFETs
17mΩ of High-Side MOSFET
Ω
4.5mΩ of Low-Side MOSFET
Ω
�½
Adjustable from 0.6V to 1.5V Output Range for
1.5V (DDR3), 1.35V (DDR3L), 1.2V (LPDDR3) and 1.2V
(DDR4)
�½
4.5V to 23V Battery Input Range
500kHz Switching Frequency
�½
Resistor Adjustable Valley Current Limit
�½
Over-/Under-Voltage Protection
�½
Internal Voltage Ramp Soft-Start
�½
Power Good Indicator
1.5A LDO (VTT)
�½
Capable to Sink and Source up to 1.5A
�½
LDO Input Available to Optimize Power Losses
�½
Require Only 10μF Ceramic Output Capacitor
μ
�½
Integrated Divider Tracks 1/2 VDDQ for VTT
�½
Accuracy
±
20mV for VTT
�½
�½
Applications
DDR3/DDR3L/LPDDR3/DDR4 Memory Power Supplies
Notebook computers
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
Simplified Application Circuit
V
IN
VIN
C
IN
VDD
C
VDD
R
PGOOD
PGOOD
S3
S5
PGOOD
S3
S5
GND
FB
PGND
VDDQ
VLDOIN
VTT
VTTSNS
VTTGND
CS
R
CS
C
VTT
V
TT
R2
BOOT
RT7241A
PHASE
C
B
L
V
DDQ
R1
C
OUT
Marking Information
00= : Product Code
V
DD
00=YM
DNN
YMDNN : Date Code
Copyright
©
2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS7241A-02 January 2017
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
