4A LDO with 0.2V dropout — the headroom math
The MAX8556ETE+ is an adjustable positive LDO regulator from Analog Devices, delivering 4A continuous output. The key number for board bring-up is the 0.2V maximum dropout at that full 4A load — meaning the input rail must stay at least 200 mV above the programmed output voltage across the load range, or the output falls out of regulation. Output is adjustable from 0.5V up to 3.4V, with a maximum input of 3.6V. That narrow input window means this part is designed for a tightly regulated 3.3V or 3.0V intermediate bus, not a raw battery rail.
Protection set and quiescent draw
Built-in protection covers overcurrent, overtemperature, short circuit, and undervoltage lockout (UVLO). The UVLO threshold is set internally — if the input dips below the dropout headroom, the regulator shuts down cleanly rather than passing a degraded output. Quiescent current is 1.6 mA typical. That is not a micropower LDO — this is a high-current regulator for a local rail, not a always-on sleep supply. Control features include an Enable pin for sequenced power-up and a Power Good open-drain output that asserts when the output is within regulation. Useful for FPGA or SoC core rail sequencing where the downstream load must wait for the rail to settle.
Housed in a 16-WQFN Exposed Pad package (also listed as 16-TQFN, 5x5 mm). Surface-mount only; the part ships in tube packaging.