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3.3V or 5V for IoT nodes from ac

Aug 19, 2023

Diodes has created a power chip that produces a regulated dc output from 85 to 300Vac mains with ~10mW no-load loss.

Called AL17051, versions are available to deliver 3.3V or 5V.

The design is not isolated – so no opto-isolator is required – which means this converter is only for applications where the circuitry cannot be touched.

Efficiency 60% with a 50mA load and 50% at 10mA.

Included in the the ~10mW no-load figure is a compulsory output load resistor (R1 in the diagram).

"The output requires a dummy load to maintain the load regulation under no-load condition," said Diodes, "This can ensure sufficient inductor energy to charge the sample-and-hold capacitor to detect the output voltage. Most applications can use a 1 to 3mA dummy load, and the dummy load can be adjusted according to the regulation. Increasing the dummy load adversely affects efficiency and no-load consumption."

Inside, there is a 700V MOS switch, and protection against: over-temperature, over-current and over-load, and there is also input under-voltage lock-out.

Packaging is SOT25.

The company will also provice automotive versions requiring specific change control (parts qualified to AEC-Q100/101/104/200, PPAP capable, and manufactured in IATF 16949 certified facilities).

Application are foreseen in home appliances, IoT wireless nodes and industrial controls.

The AL17051 product page can be found here, and the data sheet function description section is worth a read if only to understand how the IC powers itself.

Steve Bush