General Description
The RT8207P provides a complete power supply for both
DDRII/DDRIII/Low-Power DDRIII/DDRIV/Low-Power DDRIV
memory systems. It integrates a synchronous PWM buck
controller with a 1.5A sink/source tracking linear regulator
and buffered low noise reference.
The PWM controller provides the 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 constant-on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides 100ns
“instant-on” response to load transients while maintaining
a relatively constant switching frequency.
The RT8207P achieves high efficiency at a reduced cost
by eliminating the current sense resistor found in
traditional current mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous
rectifier MOSFETs. The buck conversion allows this device
to directly step down high voltage batteries for the highest
possible efficiency.
The 1.5A sink/source LDO maintains fast transient
response, only requiring 20μF of ceramic output
capacitance. In addition, the LDO supply input is available
externally to significantly reduce the total power losses.
The RT8207P supports all of the sleep state controls
placing VTT at high-Z in S3 and discharging VDDQ, VTT
and VTTREF (soft-off) in S4/S5.
The RT8207P has all of the protection features including
thermal shutdown and is available in a WQFN-20L 3x3
packages.

Applications
 DDRI/II/III/Low-Power DDRIII/DDRIV/Low-Power DDRIV
Memory Power Supplies
 Notebook Computers
 SSTL18, SSTL15 and HSTL Bus Termination

Features
 PWM Controller
 Resistor Programmable Current Limit by Low Side
RDS(ON) Sense
 Quick Load Step Response within 100ns
 1% VVDDQ Accuracy Over Line and Load
 Fixed 1.8V (DDRII), 1.5V (DDRIII) or Adjustable
0.75V to 3.3V Output Range for 1.35V (Low-Power
DDRIII), 1.2V (DDRIV) and 1.1V (Low-Power
DDRIV)
 4.5V to 26V Battery Input Range
 Resistor Programmable Frequency
 Over/Under Voltage Protection
 Internal Current Limit Ramp Soft-Start
 Drives Large Synchronous-Rectifier FETs
 Power Good Indicator
 1.5A LDO (VTT), Buffered Reference (VTTREF)
 Capable to Sink and Source 1.5A
 External Input Available to Minimize Power Losses
 Integrated Divider Tracks 1/2 VDDQ for Both VTT
and VTTREF
 Buffered Low Noise 10mA VTTREF Output
 Remote Sensing (VTTSNS)
 ±20mV Accuracy for Both VTTREF and VTT
 Supports High-Z in S3 and Soft-Off in S4/S5
 RoHS Compliant and Halogen Free