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UCC256404: PFC + LLC Converter

Rajkumar Chaurasiya
Prodigy 140 points
Part Number: UCC256404


Tool/software:

.Hi Team,

We have designed 18V and 500W PFC boost + LLC converter with universal input from 110VAC to 265VAC using PFC Boost IC UCC28180DR and LLC IC UCC256404. Power supply working very good as per expectations and requirements. 

We have already passed the compliance testing like RE, CE, EFT, Surge etc.

Currently we are failing the CEC (California Energy Commission) test. Because the standby and Maintenance power is more than the limits which are defined by the CEC.

At no load or you can in burst mode, power consumption of the power supply is 1.5W (1.5W is the input power and measured by power analyzer). This is also called the standby power. Just for clarification we have not connected any type of load at the output terminal of the power supply.

We need to reduce standby power less than 0.9W or till 0.8W. Then only Power Supply can pass the CEC test.

In standby power consumption, we connect the battery charger PCB. We measure the input power at 120VAC at no load. I mean no load across the charger PCB. This standby power should be less than 0.9W or below.

Here in standby power consumption mode, charger PCB power consumption is 0.12W only with 18VDC input voltage (Input current is 6.5mA)

In maintenance power consumption, we connect 5Ah Li-Ion battery and the battery charger PCB. We measure the input power at 120VAC when battery fully charged. This maintenance power should also less than 0.9W or below.

Here in maintenance power consumption mode, charger PCB power consumption is 0.17W only with 18VDC input voltage (Input current is 8.5mA).

Any possibility to reduce the power supply stand by power. We are struggling unable to understand what and how we can achieve 0.9W or below.

Can you please share feedback and suggestions for the burst mode power consumption of the power supply.

Please share the personal chat request then I will share the schematic. 

I will request please help because we are ready to launch the product because of CEC failure. we are unbale to launch.

Please let me know if you have any question.

Regards,

Raj Kumar