Dialog Semiconductor Debuts ZVS Chipset for High Power Density PSUs

Dialog’s zero voltage switching (ZVS) RapidCharge solution consists of the iW9801 primary-side controller and the iW709 secondary-side USB PD protocol IC. The iW709 features an integrated synchronous rectifier controller and, to ensure stability, a digital compensation loop. The high level of integration serves to save space and weight as well as to reduce the BOM count.

Image courtesy of Dialog

This new solution allows for seamless multi-mode control for up to 94% efficiency with standby power specced at under 20 mW. The high switching speed, up to 200 kHz, eliminates all audible noise.

 

What is Zero Voltage Switching?

Zero Voltage Switching (ZVS) is used with pulse width modulated (PWM) switching devices. The Turn On or Turn Off of the switch is only allowed to occur when the voltage across the output of that switching device, such as a MOSFET, is zero.

This will prevent overlap between voltage and current, which will avoid wasting the power otherwise contained within the overlap. It also prevents the harmful effects of the heat that would be engendered by that wasted power. A further advantage is that there will also be far less EMI generated, reducing the need for filtering.

 

Operation of the RapidCharge Solution

Illustrated below is a typical application of the iW9801 primary-side controller and the iW709 secondary-side device. The iW9801 includes its own primary-side OCP and OVP, employed in case of optocoupler failure.

A typical application. Image courtesy of IW9801 datasheet

The secondary side iW709 includes a USB PD (power delivery) 3.0 interface controller along with a synchronous rectifier (SR) controller and USB Type-C disconnect FETs into one package.

The iW709 outputs from 3.3 to 21 volts in steps of 20mV, along with current steps of 50mA.

The iW709 supports protections for:

• Over-voltage (OVP)
• Over-current (OCP)
• User-configurable over-temperature protection (OTP)
• Shoot-through
• brown-in/brown-out 
• VSENSE/ISENSE short
• Output short

 

Dialog’s ZVS chipset supports most standard fast charge protocols, including the popular USB power delivery PD 3.0 with Programmable Power Supply (PPS). The high switching speed allows engineers to employ a lighter, smaller transformer as well as smaller passive components. This serves to enable the production of smaller, more efficient chargers. This new chipset offers a complete solution based on built-in digital compensation, allowing for quicker and easier circuit design as compared to old-style analog approaches.

 

Dialog’s Commitment to ZVS Technology

As per Davin Lee, Senior Vice President and General Manager of the Advanced Mixed-Signal Business Group at Dialog Semiconductor, “The introduction of Dialog’s patented ZVS technology builds on our extensive AC/DC expertise and expands our addressable market into higher power density PSUs.” He goes on to state that “With this innovative ZVS chipset, customers can simply design higher power density chargers that are not only light-weight and ultra-small but also very cost-effective.”

 

Applications

The new chipset is purposed to enable engineers to design lighter, smaller, more power-dense power supplies. These will find use in power adapters for devices such as:

• Power tools
• Laptops
• Tablets
• Smartphones