In normal operation, the PWM switching frequency of the AP3127 and AP3127H controllers is internally fixed at 65 and 100kHz, respectively. However under moderate load conditions the device will enter a green mode that uses frequency fold-back to reduce the switching frequency for improved system efficiency, although a minimum switching frequency of 20kHz ensures any audible noise is avoided. Under no-load or light-load conditions, the ICs use a burst mode to minimise standby power while a built-in frequency dithering function reduces EMI emissions.
In addition to offering superior power control with higher average efficiency than pin-equivalent competitive products, the AP3127/H controllers include a comprehensive range of protection features to ensure stable, robust and reliable operation. These cover various overload and fault conditions such as over-current, secondary-side over-voltage, internal over-temperature and secondary-side under-voltage protection, which protects a supply if its output cable is shorted.
The AP3127/H PWM controllers are supplied in standard SOT26 packages, priced at $0.34 each in 1,000 unit quantities.