RT9643

Pinout




Description

The RT9643 is a combo regulator which is compliant to ACPI specification for desktop/motherboard power management and system application. The RT9643 part features one switch regulator for DDR memory VDDQ power; three linear regulators including 1.5Amp peak sourcing/sinking capability regulator for DDR VTT, a 1.2V ultra-low-dropout linear controller for chipset miscellaneous power, a 3.3VSB power with 1.25Amp peak current capability; and 2 dual power control including 5VDL, and 3.3VDL control for S3 and S5 system power. The RT9643 part totally feature 5 sets power which are compliant to ACPI specification into a single small footprint package VQFN-24L 5x5.
The RT9643 part is generally operated to conform to ACPI specification, in S3 state, there are only VDDQ and 3.3VSB regulators remain on while the VTT and ULDO regulators are off. In the transition from S3 to S0, an external SS capacitor is attached for linear regulators to control its slew rates respectively to avoid inrush current induced. Moreover, the PGOOD signal raises high in S0 stage while all 3 regulators go stable. In the stage of S5 (EN = 0), there only 3.3VSB LDO remain on, while the other regulators are powered down. The VDDQ PWM regulator is a voltage mode implementation with external compensation to provide high load transient response. The VTT is regulated to follow 1/2 of VDDQ and is capable of sourcing or sinking 1.5A peak currents.