New Industry Products

Power Integrations’ New Device Family Reduces Standby Power

November 08, 2019 by Roland Ackerman

This article highlights Power Integrations CAPZero-3 (CAP300DG) that enable designers to easily meet IEC60335 safety approvals for major appliances.

CAPZero-3 X-Capacitor Discharge ICs Meet IEC60335

Power Integrations announced CAPZero-3, the latest generation of the company’s energy-saving X-capacitor discharge ICs. Two-terminal CAPZero-3 ICs (CAP300DG) enables designers to easily meet IEC60335 safety approvals for major appliances and cover all capacitor values from 100nF to 6µF.

IEC60335 is the discharge safety standard for all appliances. To protect the user from an electrical hazard, it requires the voltage across the input X capacitor to discharge to less than 34 V within less than one second after the AC is removed. CAPZero-3 ICs block current flow through the X-capacitor discharge resistors when the AC voltage is connected, and automatically discharge X capacitors through those resistors when the AC is disconnected. CAPZero-3 ICs simplify EMI filter designs while permitting the use of larger X capacitors, which in turn enables smaller inductive components to be used with no resulting change in power consumption.

CAPZero-3 ICs can be placed before or after a system’s input fuse. Devices deliver high common-mode surge immunity so that no external ground connection is necessary, and feature a high differential surge withstand due to 1000V internal MOSFETs. Creepage on the package and PCB is maintained at >4mm. Comments Edward Ong, product manager, Power Integrations: “With the launch of the new CAPZero-3 ICs, designers can use one part to address a large range of applications in small and major appliances that require X capacitor values from 100 nF to 6 µF.”

CAPZero-3 devices are safety-certified to CB and Nemko requirements so developers do not need to perform a separate safety test on the X-capacitor discharge circuit of the power supply. Devices are available now, priced at $0.31 in 1,000 piece quantities.



  • All AC-DC converters with X capacitors of 100nF up to 6µF
  • Appliances requiring ErP Lot 6 compliance
  • Adapters requiring ultra-low no-load consumption
  • All converters requiring very low standby power
  • Lossless generation of zero-crossing signal



When AC voltage is applied, CAP300DG blocks current flow in the X capacitor safety discharge resistors, reducing the power loss to less than 5mW, or essentially zero at 230VAC. When AC voltage is disconnected, CAP300DG automatically discharges the X capacitor by connecting the series discharge resistors. This operation allows total flexibility in the choice of the X capacitor to optimize differential mode EMI filtering and reduce inductor costs, with no change in power consumption.

Designing with CAP300DG is simply a matter of selecting the appropriate external resistor values for the X capacitor value being used to achieve the necessary time constant. The simplicity and ruggedness of the two terminal CAP300DG IC make it an ideal choice in systems designed to meet ErP Lot 6 requirements.



CAP300DG meets safety requirements even if placed before the system input fuse. If a short-circuit is placed between D1 and D2 terminals of CAP300DG, the system is identical to existing systems where CAP300DG is not used. With regard to open circuit tests, it is not possible to create a fault condition through a single pin fault (for example lifted pin test) since there are two pins connected to each of D1 and D2. If several pins are lifted to create an open circuit, the condition is identical to an open circuit X capacitor discharge resistor in existing systems where CAP300DG is not used. If redundancy against open circuit faults is required, two CAP300DG and R1/R2 configurations can be placed in parallel.


Discharge Operation

To meet the safety regulations of appliances, when the AC supply is disconnected, CAP300DG will discharge the X capacitor to <34V levels according to the above functional description.


Product Highlights

  • Meets IEC 60335 X capacitor discharge of <34V in <1sec
  • One part to cover X capacitor values from 100nF to 6µF
  • Blocks current through X capacitor discharge resistors when AC voltage is connected
  • Automatically discharges X capacitors through discharge resistors when AC is disconnected
  • Simplifies EMI filter design – larger X capacitor allows smaller inductive components with no change in consumption
  • Only two terminals – meets safety standards for use before or after system input fuse
  • >4mm creepage on package and PCB
  • Self-supplied – no external bias required
  • High common mode surge immunity – no external ground connection
  • High differential surge withstand – 1000V internal MOSFETs
  • NEMKO and CB certification pending.


EcoSmart – Energy Efficient

  • <5mW consumption at 230VAC for all X capacitor values


About the Author

Roland R. Ackermann has been a technology journalist since 1957, covering electronics, engineering and manufacturing/automation. He has been a freelance journalist since 1996, publishing work in Elektronik Journal, was editor in chief of Electronik Embedded System and verlagsweltMAGAZIN, and also wrote numerous articles in German and English publications and newspapers. He was a regular column writer in E&E Faszination Elektronik and is now a correspondent for Bodo's Power Systems. Ackermann holds talks at international venues, moderates panel discussions, and organizes events.