TI claims first for a primary-regulated, “zero standby power”, higher-power AC/DC PSU

March 09, 2015 // By Graham Prophet
Using the definition of zero-standby power as in the International Electrotechnical Commission (IEC) 62301 clause 4.5, Texas Instruments has assembled a power supply design with smart load monitor, and wake-up feature that enables rapid step response with smallest output capacitors for 75-W flyback converters

Presented as the first zero standby power controller chipset with the lowest standby power consumption for AC/DC flyback power supplies up to 75W, the UCC28730 primary-side regulation (PSR) flyback controller with 700-V startup switch and UCC24650 wake-up monitor supports 5- to 24-V output voltages and helps designers create smaller, more efficient power supplies

A major design limitation with existing primary-side regulation power supplies, TI adds, is poor transient response performance while trying to maintain low standby power. The UCC28730 and UCC24650 chipset achieves zero standby power consumption while achieving the best transient response performance possible. Besides reducing cost by eliminating feedback components such as an optocoupler and TL431, TI’s voltage droop-detection feature in the UCC24650 wake-up controller enables the use of small output capacitors while maintaining a narrow-output voltage-regulation window with zero- to full-load transients.

Lowest system-standby power consumption enables zero standby power consumption without any additional components in standard flyback designs up to 20W and is extendable up to 75W using the intelligent sleep function for adaptive relay control.


The 700-V primary-side regulation controller (UCC28730) eliminates the need for an optocoupler and associated feedback components, reducing overall system cost while increasing reliability.


The smart wake-up function enables 50% lower-value output capacitors while maintaining a tight output regulation window with zero to full load steps, improving efficiency and saving space.

An intelligent sleep function adapts to converter-loading conditions and is able to disable system functions, adapt for AC relay control, or disable the synchronous rectifier at no load.

The 200-V secondary-side wake-up controller (UCC24650) is compatible with 5- to 24-V output voltage designs without the need for external clamps on Vdd or wake.


The UCC24650 is also compatible with TI’s UCC28633 PSR controller, which enables peak power delivery twice that of other configurations without a proportionate increase in magnetics size, making it optimal for applications such a printers, audio, gaming and industrial power supplies.

TI supports the