PWM controllers enable smaller, greener power adapters up to 40W

The new PrimAccurate iW1699 and iW1760 digital pulse width modulation (PWM) controllers from iWatt Inc. allow power adapter designers to meet stringent emerging global energy regulations for AC/DC power adapters, which require them to consume less than 100mW standby power, with the added benefits of a lower BOM (bill of materials) cost, and smaller overall adapter size.

The iW1699 is optimized for applications up to 12W with ultra-low standby power of less than 30mW to address the needs of smart phone and media tablet applications. The iW1760 is designed for applications requiring higher power, up to 40W, with less than 50mW standby power, including set top boxes, home networking devices, and a wide range of household appliances.

The iW1699 and iW1760 build on iWatt’s iW1691 digital controller, but enabling even lower standby power, a smaller BOM cost, and added design flexibility. Both parts use iWatt’s patented PrimAccurate primary-side control, which 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 less than 30mW no-load standby power consumption of the iW1699 is 70% lower than iWatt’s earlier iW1691 controller, while using smaller, 20µF/820µF input and output capacitors, versus 20µF/1,300µF for the iW1691. This further reduces both the BOM size and cost and allows ultra-compact power adapters as small as 2cm x 2cm x 1.7cm. This results in 10W power adapters in a form factor previously associated with the smallest 5W devices.

Both the iW1699 and iW1760 offer added design flexibility compared to the existing iW1691 part by adding a user-configurable, five-level cable-drop compensation (CDC) option. Because it is controlled via a configuration pin option, the CDC option simplifies product options, ordering and inventory challenges. The configuration pin also provides both CDC configuration and supplemental over-voltage protection (OVP) control for lower BOM cost.

The iW1699 and iW1760 ICs feature iWatt’s EZ-EMI®, an internal EMI (electromagnetic interference) technique that uses valley mode switching to reduce EMI, simplify manufacturing and meet international EMI standards. Both devices offer full protection from fault conditions, as well as over-voltage, over-current and over-temperature protection.

iW1699, iW1760 Key Features

• iW1699: optimized for up to 12W, < 30mW standby power consumption
• iW1760: optimized for up to 40W, < 50mW standby power consumption
• Patented PrimAccurate primary-side control increases reliability, reduces solution size, lowers BOM cost
• User-configurable, five-level cable drop compensation for design flexibility
• Patent-pending quasi-resonant control optimizes efficiency at all loads
• Proprietary, optimized PWM switching frequency: iW1699 = 89kHz max; iW1760 = 79kHz max
• Patented, adaptive multi-mode PWM/PFM optimizes efficiency, EMI, and power consumption

Pricing and Availability
The iW1699 and iW1760 are available now in production quantities. They come in a standard, low-cost, 8-lead SOIC package. Samples are available at $0.30 for both the iW1699 and the iW1760 in 1000-piece quantities.

More information iW1699, iW1760.