4A Ultra-Low-Input-Voltage LDO Regulators

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The MAX8556/MAX8557 low-dropout linear regulators operate from input voltages as low as 1.425V and are able to deliver up to 4A of continuous output current with a typical dropout voltage of only 100mV. The output voltage is adjustable from 0.5V to VIN - 0.2V.

Designed with an internal p-channel MOSFET pass transistor, the MAX8556/MAX8557 maintain a low 800µA typical supply current, independent of the load current and dropout voltage. Using a p-channel MOSFET eliminates the need for an additional external supply or a noisy internal charge pump. Other features include a logic-controlled shutdown mode, built-in soft-start, short-circuit protection with foldback current limit, and thermal-overload protection. The MAX8556 features a POK output that transitions high when the regulator output is within ±10% of its nominal output voltage. The MAX8557 offers a power-on reset output that transitions high 140ms after the output has achieved 90% of its nominal output voltage.

The MAX8556/MAX8557 are available in a 16-pin thin QFN 5mm x 5mm package with exposed paddle.
MAX8556, MAX8557: Typical Operating Circuit MAX8556, MAX8557: Typical Operating Circuit Enlarge+

Key Features

  • 1.425V to 3.6V Input Voltage Range
  • Guaranteed 4A Output Current
  • ±1% Output Accuracy Over Load/Line/Temperature
  • 100mV Dropout at 4A Load (typ)
  • Built-In Soft-Start
  • 800µA (typ) Operating Supply Current
  • 150µA (max) Shutdown Supply Current
  • Short-Circuit Current Foldback Protection
  • Thermal-Overload Protection
  • ±10% Power-OK (MAX8556)
  • 140ms Power-On Reset Output (MAX8557)
  • Fast Transient Response
  • 16-Pin Thin QFN (5mm x 5mm) Package


  • Automated Test Equipment (ATE)
  • Base Stations
  • Networking
  • Optical Modules
  • Point-of-Load Supplies
  • Servers and Storage Devices

See parametric specs for Linear Regulators (133)

Part NumberRegulatorsVIN
Low Batt./ Pwr. Fail OutPOK/Reset Thresh.
WatchdogReverse Batt. Protect.Oper. Temp.
minmaxminmaxtypmaxnomSee Notes
MAX8556 to +85
$4.11 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX8556EVKIT: Evaluation for the MAX8556
Product Reliability Reports: MAX8556.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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Related Resources

Type ID Title
Evaluation Board4445MAX8556EVKIT Evaluation for the MAX8556