5V/3.3V or Adjustable, Low-Dropout, Low-IQ, 500mA Linear Regulators

Industry's Smallest 500mA LDO in SO-8 Footprint Handles Up to 1.8W Power Dissipation

Please check latest availability status for a specific part variant.


The MAX603/MAX604 low-dropout, low quiescent current, linear regulators supply 5V, 3.3V, or an adjustable output for currents up to 500mA. They are available in a 1.8W SO package. Typical dropouts are 320mV at 5V and 500mA, or 240mV at 3.3V and 200mA. Quiescent currents are 15µA typ and 35µA max. Shutdown turns off all circuitry and puts the regulator in a 2µA off mode. A unique protection scheme limits reverse currents when the input voltage falls below the output. Other features include foldback current limiting and thermal overload protection.

The output is preset at 3.3V for the MAX604 and 5V for the MAX603. In addition, both devices employ Dual Mode™ operation, allowing user-adjustable outputs from 1.25V to 11V using external resistors. The input voltage supply range is 2.7V to 11.5V.

The MAX603/MAX604 feature a 500mA P-channel MOSFET pass transistor. This transistor allows the devices to draw less than 35µA over temperature, independent of the output current. The supply current remains low because the P-channel MOSFET pass transistor draws no base currents (unlike the PNP transistors of conventional bipolar linear regulators). Also, when the input-to-output voltage differential becomes small, the internal P-channel MOSFET does not suffer from excessive base current losses that occur with saturated PNP transistors.
MAX603, MAX604: Typical Operating Circuit MAX603, MAX604: Typical Operating Circuit Enlarge+

Key Features

  • 500mA Output Current, with Foldback Current Limiting
  • High-Power (1.8W) 8-Pin SO Package
  • Dual Mode™ Operation: Fixed or Adjustable Output from 1.25V to 11V
  • Large Input Range (2.7V to 11.5V)
  • Internal 500mA P-Channel Pass Transistor
  • 15µA Typical Quiescent Current
  • 2µA (Max) Shutdown Mode
  • Thermal Overload Protection
  • Reverse-Current Protection


  • 1.25V to 11V Adjustable Regulators
  • 5V and 3.3V Regulators
  • Automotive Electronics
  • Pagers and Cell Phones
  • Portable Instrumentation
  • Solar-Powered Instruments

See parametric specs for Linear Regulators (133)

Part NumberRegulatorsVIN
Preset VOUT
Low Batt./ Pwr. Fail OutWatchdogReverse Batt. Protect.Oper. Temp.
minmaxminmaxtypmaxSee Notes
MAX603 12.711.551.311.50.3250050NoNoNo0 to +70
SOIC (N)/8
$2.06 @1k
MAX604 3.30.635
-40 to +85
0 to +70
SOIC (N)/8
$1.95 @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.
Product Reliability Reports: MAX604.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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