AC-DC chip allows tiny wall plug adapter
iWatt has launched two ac-dc digital PWM controllers that can be used in low-stand-by wall plug adapters.
iW1699 delivers up to 12W for phones and tablets, with <30mW stand-by.
iW1760 is for applications up to 40W, with <50mW low stand-by for set top boxes, home networking devices, and household appliances.
“They are based on the company’s newest controller platform and allow designers to meet emerging global energy regulations for ac-dc power adapters, including the proposed 2013 US regulation RIN: 1904-AB57, which requires they consume less than 100mW stand-by power,” said iWatt.
Compared with the firm’s earlier iW1691, on which the two new chips build, iW1699′s stand-by power is 70% lower, and it uses 20/820µF input and output capacitors, compared with 20/1,300µF.
“This allows power adapters as small as 2x2x1.7cm,” said iWatt. “It results in 10W power adapters in a form factor previously associated with 5W devices.”
Both iW1699 and 1760 have a pin-configurable, five-level cable-drop compensation option.
Control is quasi-resonant, and adaptive multi-mode PWM/PFM is used to optimises efficiency at different power levels. Valley-mode switching reduces EMI.
Maximum PWM frequency is 89kHz for the 1699 and 79kHz for the 1760.