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

Active: In Production.

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.

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