Marvell targets digital power for lower-power laptop, desktop supplies

Digitally-controlled power supplies – ones where the control loop is controlled digitally – have so far found favor in larger power applications. For example, Coldwatt’s ac-dc power supply, based on the Silicon Labs’ C8051F30x digital power control chip, is aimed at server installations and ranges from 1200-1625W. Now Marvell is introducing two new digital control chips, the 88EM8041 and 88EM8011 that target smaller ac-dc supplies used by laptops (up to 80W) and desktops (up to 300W). The chips also introduce digital power factor control (PFC) for these smaller  supplies. Currently, EnergyStar standards don’t require PFC for laptop and desktop supplies – but it’s coming in future revisions because of PFC’s ability to increase power efficiency.

The chips use Marvell’s proprietary DSP to optimize power throughout the cycle by changing from pulse-width modulation (PWM) to pulse-frequency modulation (PFM) to keep the peak current at the lowest level. This architecture can also intelligently adjust the current threshold limit for constant power to manage differences in worldwide universal voltages which range from 90V to 260V. Marvell claims the chips can reduce power supply size by a third, and BOM count by as many as 20 parts, and increase power supply efficiency to 85%. The chips will sell at under $2.00 per unit in 1K quantities.