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