The APW8819 integrates a synchronous buck PWM controller to generate VDDQ, a sourcing and sinking LDO linear regulator to generate VTT. It provides a complete power supply for DDR2 and DDR3 memory system. It offers the lowest total solution cost in system where space is at a premium. The APW8819 provides excellent transient response and accurate DC voltage output in PFM Mode. In Pulse Frequency Mode (PFM), the APW8819 provides very high efficiency over light to heavy loads with loading-modulated switching frequencies. The APW8819 is equipped with accurate current-limit, output under-voltage, and output over-voltage protections. A Power-On- Reset function monitors the voltage on VCC prevents wrong operation during power on. The LDO is designed to provide a regulated voltage with bi-directional output current for DDR-SDRAM termination. The device integrates two power transistors to source or sink current up to 1.5A. It also incorporates current-limit and thermal shutdown protection. An internal resistor divider is used to provide a half voltage of VDDQSNS for VTTREF and VTT Voltage. The VTT output voltage is only requiring 20mF of ceramic output capacitance for stability and fast transient response. The S3 and S5 pins provide the sleep state for VTT (S3 state) and suspend state (S4/S5 state) for device, when S5 and S3 are both pulled low the device provides the soft-off for VTT and VTTREF.The APW8819 is available in 3mmx3mm 20-pin QFN and 3mmx3mm 16-pin TQFN packages.