New Industry Products

Power Integrations Debuts a Family of ZVS Flyback Switcher ICs

June 06, 2021 by Gary Elinoff

The GaN-based units combine with the company’s ACF controller ICs to facilitate the design of USB-C mobile chargers

Power Integrations’ InnoSwitch4-CZ family of high frequency, zero voltage switching (ZVS) flyback switcher ICs incorporate a 750 V primary switch using Power Integrations’ PowiGaN technology. Combined with the company’s ClampZero active clamp flyback (ACF) controller, the pair makes it possible to improve the efficiency of even the smallest form factor flyback power converters.

Image courtesy of Power Integrations (PI)
Image courtesy of Power Integrations (PI)


An Early Collaboration with Anker

Rather going the popular route of creating a dedicated reference design, PI has partnered with charger manufacturer Anker, who utilize the InnoSwitch4-CZ and ClampZERO chips in the design of their Nano II series of USB-C chargers.

As per Steven Yang, CEO at Anker, "We are excited to work with Power Integrations as their exclusive launch partners for their InnoSwitch4 chipsets. The InnoSwitch4-CZ was a natural choice for Anker's new Nano II series of USB-C chargers. Its outstanding levels of integration and efficiency are key to the Nano II series’ extremely compact design.” 

Image courtesy of Anker. 
Image courtesy of Anker


And, as commented by Balu Balakrishnan, CEO of Power Integrations, “The introduction of the InnoSwitch4-CZ family of ICs marks a significant milestone for GaN technology. PowiGaN switches, in conjunction with our active clamp solution – ClampZero, enable a highly efficient design and an extremely compact form-factor. We’re pleased to have worked closely with the Anker team to bring this new class of mobile charger to market.” 


InnoSwitch4-CZ Family

Members of the InnoSwitch4-CZ family combine a high-voltage power switch and both primary-side and secondary-side controllers in a single package. The unit switches at frequencies of up to 140 kHz and can support flyback designs delivering up to 110 watts. 

Its unique FluxLink inductive coupling feedback methodology employs the package lead frame and bond wires to transfer needed information from the secondary controller to the primary controller. 

The unit’s primary controller is a zero voltage switching (ZVS) flyback controller. It can operate in discontinuous conduction mode (DCM) and in continuous conduction mode (CCM), with virtually no switching loss. 

Typical application. Image courtesy of InnoSwitch4-CZ family datasheet
Typical application. Image courtesy of InnoSwitch4-CZ family datasheet


The secondary controller consists of a transmitter circuit that is, as described,  magnetically coupled to the primary receiver. There is also constant voltage and constant current control circuitry. Other features include a synchronous rectifier FET driver and, for optimal ZVS in DCM mode, a QR mode circuit. Also included are the various necessary protection features. 


The ClampZero Family

These units accept input voltages of 85 to 265 VAC. They support output powers analogous to those of the InnoSwitch4-CZ units. The units are meant to work together. Indeed, the ClampZero’s datasheet sports the same diagram as illustrated above, only with the ClampZero’s portion highlighted.

The ClampZero IC serves to eliminate wasted inductive energy by recycling it. The device includes a high-side power switch and level shifted self-biased controller, the latter communicates with a low-side transceiver, itself connected to the InnoSwitch4 primary controller.

The ClampZero ensures ZVS across in both CCM and DCM operating modes and in all line and load conditions. This is achieved through the precise coordination of timing between the ClampZero’s turn off and the InnoSwitch4 power switch’s turn-on, completely removing turn-on losses.


Physical and Environmental Characteristics

Both the InnoSwitch4-CZ Family and the ClampZERO chips are:

  • Halogen free
  • RoHS compliant