Primary-Side Switcher for AC/DC Power Control

Sept. 25, 2012
iWatt Inc. announced its latest AccuSwitch primary-side driver with an internal power switch rated to 800V for universal AC input.

iWatt Inc. has announced its latest AccuSwitch primary-side driver with an internal power switch rated to 800V for universal AC input. The new iW1816 digital pulse width modulation (PWM) driver is designed to support high capacitance loads (up to 6,000µF) at up to 5W. The device also includes an adaptively controlled soft start, which enables fast start-up for a wide range of output voltages from 5V to 12V and higher, while driving a large capacitive load. In addition, the iW1816 is specifically designed to enable under 100mW system standby power, even with close to 50mW at light load, to meet the increasing demands for high energy efficiency in standby mode. AccuSwitch drivers feature all the benefits of iWatt's PrimAccurate technology, namely lower bill of materials (BOM) cost, small solution size and higher reliability, with the added ease of use of an internal high voltage power switch.

The iW1816 was developed in conjunction with manufacturers of home appliances and is optimized to meet the requirements of demanding power supply applications in smart meters, industrial control applications, microwave ovens and household appliances. It is designed to operate in noisy environments and drive large capacitance loads while maintaining a low BOM cost.

iWatt's patented PrimAccurate primary-side control uses proprietary digital algorithms to eliminate the need for a secondary-side regulator and optical feedback isolator, lowering the total BOM cost, reducing the overall solution size, and improving reliability. PrimAccurate technology enables accurate control of the output over a wide range of operating conditions, and ensures tight load and line regulation, along with full protection from fault conditions, without costly additional components.

The iW1816 features iWatt's EZ-EMI®, an internal EMI (electromagnetic interference) technique that uses valley mode switching to reduce EMI, simplify manufacturing, reduce the need for input filtering and meet international EMI standards. The device offers full protection from fault conditions, such as over-voltage protection, over-current protection, and over-temperature protection.


  • Internal power switch rated to 800V
  • Accurate voltage (+/- 3%) and current control (+/- 3%)
  • Start-up with large output capacitance (6,000µF)
  • Optimized for 12V output
  • Patented PrimAccurate primary-side control increases reliability, reduces solution size, lowers BOM cost

The iW1816 is available now in production quantities. The device comes in a standard, low-cost, 7-lead SOIC package. Samples are available at $0.39 for the iW1816 in 1000-piece quantities.


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