Answer:
Several solutions exist:
DDR4 operates at a voltage between 1.2 V and 1.4 V with a frequency between 800MHz and 2133 MHz.
The MAX1510/MAX17510 DDR linear regulators source and sink up to 3A peak (typ) using internal n-channel MOSFETs. These linear regulators deliver an accurate 0.5V to 1.5V output from a low-voltage power input (VIN = 1.1V to 3.6V).
The MAX8794 is an upgrade to the MAX1510. The MAX8794 has improved drop out performance.