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

特性 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