General Description

The RT8231A/B provides a complete power supply for

DDR2/DDR3/DDR3L/LPDDR3/DDR4/LPDDR4 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 low quiescent 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 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 RT8231A/B 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 a 10μF ceramic output capacitor.

In addition, the LDO supply input is available externally

to significantly reduce the total power losses. The

RT8231A/B 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 RT8231A/B provides protections including OVP, UVP,

and thermal shutdown. The RT8231A/B is available in the

WQFN-20L 3x3 package.

Applications

 DDR2/DDR3/DDR3L/LPDDR3/DDR4/LPDDR4 Memory

Power Supplies

 Notebook computers

 SSTL18, SSTL15 and HSTL bus termination