Complete Power IC for Low-Cost PDAs

Active: In Production.

The MAX1552 is a complete power-management chip for low-cost personal digital assistants (PDAs) and portable devices operating from a 1-cell lithium-ion (Li+), or 3-cell NiMH battery. It includes all the regulators, outputs, and voltage monitors necessary for small PDAs, while requiring a bare minimum of external components. This device features four linear regulators, a step-up DC-to-DC converter for LCD bias, a microprocessor reset output, and low battery detection in a miniature QFN package. For a compatible Li+ charger for both USB and AC adapter inputs, refer to the MAX1551.

The four linear regulators feature PMOS pass elements for efficient low-dropout operation. The MAIN LDO supplies 3.3V at over 300mA. An SD card slot output supplies 3.3V at 200mA. The COR1 LDO outputs 1.5V at 200mA and the COR2 LDO supplies 1.8V at 20mA. The SD output and COR2 LDOs have pin-controlled shutdown. For other output voltage combinations, contact Maxim.

The step-up DC-to-DC converter features an on-board MOSFET and true shutdown when off. This means that during shutdown, input power is disconnected from the inductor so the boost output falls to 0V rather than remaining one diode drop below the input voltage.

A µP reset output clears when the input voltage rises to 3.4V to ensure an orderly start. A low-battery output warns the system of impending power loss for safe shutdown. Thermal shutdown protects the die from overheating.

The MAX1552 operates from a 3.1V to a 5.5V supply voltage and consumes 50µA no-load supply current. It is packaged in a 1.3W, 16-pin thin QFN with a power pad on the underside of the package. The MAX1552 is specified for operation from -40°C to +85°C.

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