Digital PWM controllers break new ground in ultra-low standby power in 12-w to 24-w power supplies

October 25, 2012 // By Paul Buckley
iWatt claims to have raised the bar for no-load standby power consumption and efficiency in 12 W to 24 W power adapter and charger applications with the iW1761 and iW1762 digital pulse width modulation (PWM) controllers.

The new devices expand iWatt’s latest PrimAccurate controller platform, lowering power draw in standby mode to 10 mW at up to 12 W output power (iW1761) and 20 mW at up to 24 W output power (iW1762). The iW1761 and iW1762 controllers offer even lower standby power consumption than iWatt’s recently announced iW1699 and iW1760 with their respective 30 mW (at 12 W)  and 50 mW (at 40 W) standby power consumption. All four devices exceed current energy standards in the markets in which the company competes, including the proposed stringent 2012 USA. DoE(1) regulation requiring under 100 mW AC/DC adapter standby power consumption and tighter efficiency requirements. Like the previous iWatt parts, both the iW1761 and iW1762 enable high power density in an ultra-small overall adapter size.

The iW1761 and iW1762 meet the compact size and low power requirements of next-generation compact media tablet power chargers and adapters. They also offer significantly greener and smaller solutions for AC/DC power adapters in a wide range of electronic products that remain permanently plugged in to the wall in standby mode, including set top boxes, satellite receivers and home networking equipment.

In addition to very low standby power consumption, these new controllers provide good dynamic load response (DLR). Power supplies that achieve low standby power typically do so by entering a standby operating mode. However, when a load is applied, they need to ‘wake up’ quickly to keep the output voltage from dropping too low. Dynamic load response is determined by the speed at which the system wakes up and responds to changes in the power load. The iW1761 and iW1762 offer the ultimate in low standby power with good DLR, while the recently announced iW1699 and iW1760 give designers options for higher DLR performance.

iWatt’s ultra-low standby power AC/DC controller platform employs the company’s patented PrimAccurate primary-side control. This unique technology uses proprietary digital algorithms to eliminate the need for a