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.
Feature
- PWM Controller► Adjustable Current Limit with Low-Side RDS(ON) Sensing► Low Quiescent Supply Current► Quick Load-Step Response within 100ns► 1% VVDDQ Accuracy Over Line and Load► Adjustable 0.675V to 3.3V Output Range for 1.8V (DDR2), 1.5V (DDR3), 1.35V (DDR3L), 1.2V (LPDDR3), 1.2V (DDR4) and 1.1V (LPDDR4)► 4.5V to 26V Battery Input Range► Resistor Adjustable Frequency► Over-/Under-Voltage Protection► Internal Voltage Ramp Soft-Start ► Drives Large Synchronous Rectifier MOSFETs► Power Good Indicator
- 1.5A LDO (VTT), Buffered Reference (VTTREF)► Capable to Sink and Source Up to 1.5A► LDO Input Available to Optimize Power Losses► Requires Only 10μF Ceramic Output Capacitor► Integrated Divider Tracks 1/2 VDDQ for both VTT and VTTREF► Accuracy ±20mV for both VTTREF and VTT► Supports High-Z in S3 and Soft-Off in S4/S5
- RoHS Compliant and Halogen Free
Applications
- DDR2/DDR3/DDR3L/LPDDR3/DDR4/LPDDR4 Memory Power Supplies
- Notebook computers
- SSTL18, SSTL15 and HSTL bus termination
