General Description

The AS1321 is a high-efficiency step-up DC-DC converter designed to generate a fixed output voltage of +5.0V.

The AS1321 achieves an efficiency of up to 96. The minimum input voltage is +1.5V, the output voltage is fixed at +5.0V, and output current is up to 130mA (@ 2V VBATT).

In order to save power the AS1321 features a shutdown mode, where it draws less than 1µA. In shutdown mode the battery is connected directly to the output enabling the supply of real-time-clocks.

The AS1321 provides a power-on reset output that goes high-impedance when the output reaches 90 of its regulation point.

The SHDNN trip threshold of the AS1321 can be used as an input voltage detector that disables the device when the battery voltage falls to a predetermined level.

An internal synchronous rectifier is included, which is parallel with the external Schottky diode.

The AS1321 is available in a 6-pin SOT23 package.

Key Features

■ Fixed Output Voltage: +5.0V

■ Output Current: Up to 130mA (@ 2V VBATT)

■ Internal Synchronous Rectifier

■ Shutdown Mode Supply Current: Less Than 1µA

■ Efficiency: Up to 96

■ Minimum Input Voltage: +1.5V

■ Accurate Shutdown Low-Battery Cutoff Threshold

■ Battery Input Connected to Pin OUT in Shutdown Mode for Backup Power

■ 6-pin SOT23 Package

Applications

The AS1321 is ideal for low-power applications where ultra-small size is critical as in medical

diagnostic equipment, hand-held instruments, pagers, digital cameras, remote wireless

transmitters, cordless phones, and PC cards.

The device is also perfect as a local +5.0V supply or as a battery backup.