Power Integrations Unveils Capacitor Discharge ICs for Standby Power Reduction

Power Integrations has expanded its lineup of X-capacitor discharge ICs with the release of the CAPZero-4 family. Designed to address the growing need for ultra-low standby power electronics in a constrained physical footprint, the new components target demanding consumer appliances, displays, adapters, and industrial machinery.

The CAPZero-4 series continues the company’s approach to X-capacitor discharge management by effectively disconnecting the energy-consuming discharge resistor from the circuit while the AC-DC power supply is connected to an active AC voltage. Once the device is unplugged, the IC automatically reconnects the series resistors to safely bleed off the residual power stored in the X-capacitor.

Power Integrations’ CAPZero-4 capacitor discharge ICs.

An X-capacitor is a type of safety-certified capacitor connected across the AC line (line-to-line or line-to-neutral) to suppress electromagnetic and radio-frequency interference (EMI/RFI).

Minimizing Standby Power Losses

A primary advantage of the CAPZero-4 family is its ability to significantly cut system no-load and standby input power. By blocking current flow through the safety discharge resistors during normal operation, the IC reduces total power loss by up to 1000 mW. The device itself consumes less than 1 mW—specifically remaining below 0.75 mW at 230 VAC—enabling zero-watt no-load operation.

Company representatives note that this architecture frees up more of the available power budget for the actual load during standby mode, easing compliance challenges for designers. This capability is particularly valuable in power supply designs where total system standby limits can be as tight as 300 mW or less.

Furthermore, removing the static power drain gives engineers total flexibility when selecting an X-capacitor. Designers can optimize differential mode EMI filtering by utilizing larger capacitance values (ranging from 100 nF to 6 μF). This approach helps reduce the size and cost of the required inductive components without incurring any subsequent power consumption penalty. More information is available in the CAPZero-4 data sheet.

Thermal Resilience and Voltage Architecture

Built to maintain continuous function across strenuous operating environments, the CAPZero-4 ICs feature an extended thermal operating range of -40°C to +125°C. This exceptional temperature tolerance ensures the hardware remains viable for harsh outdoor installations and industrial control enclosures alongside climate-controlled consumer applications.

The internal architecture relies on integrated MOSFETs with a 900 V breakdown rating, yielding high differential surge withstand and high common-mode surge immunity. As a self-supplied, two-terminal component, the CAPZero-4 provides a lossless zero-crossing (ZC) signal to the system MCU and does not require an external bias or a ground connection.

Dual Certification and Streamlined Design

Meeting stringent regulatory parameters is vital for modern power systems. The encapsulated SO-8 package features greater than 4 mm of creepage on both the component itself and the printed circuit board, fully meeting safety standards for use either before or after a system input fuse. The hardware fulfills multiple global safety mandates, including IEC 60335, EN/IEC 62368-1 (NEMKO), UL 62368-1, and GB 4943.1 (CQC).

Schematic with CAP400DG from the CAPZero-4 family

To accelerate design cycles and ease inventory demands, the new ICs offer straightforward drop-in replacement capabilities. Because they share pin-to-pin and package compatibility with prior-generation CAPZero-3 devices, engineers can migrate systems to the new family without necessitating a full board redesign. Implementing the CAPZero-4 in a circuit merely requires selecting the proper external resistor values to establish the correct discharge time constant for the chosen X-capacitor.

According to Power Integrations, the 4th generation of the CAPZero family represents an ideal solution for engineers managing tight standby requirements and ErP Lot 6 compliance. By delivering enhanced power efficiency, robust thermal performance, and global safety certification within a familiar footprint, the CAPZero-4 establishes a practical benchmark for mitigating no-load power losses in AC-DC converters.

All images used courtesy of Power Integrations.