Design tool helps with LCC resonant converters

“Power factor correction plus LCC resonant topology for constant current output has proven to offer outstanding efficiency combined with a large output voltage range in high-power LED lighting applications,” according to the company. The “topology is 5 to 6% more efficient than other commonly used two-stage topologies. However, the design of LED drivers with this topology is highly time-consuming.”

Given the required electrical input and output values and some magnetic component properties, the tool creates a “non-iterative but accurate LCC”, said Infineon, to allow the resonant tank parameters – series resonant L, series resonant C, parallel resonant C and transformer turns-ratio – to be optimised.

It uses assumptions including: average input bus voltage is controlled by a PFC, no magnetising current and that: half-bridge dead-time, transformer loss, mosfet resistance, output diode resistance and LED dynamic resistance are all zero.

The tool accompanies an application note (see below) on using the company’s ICL5102 (and ICL5102HV), an IC which can implement both PFC and resonant controller, operating at up to 500kHz if needed. It is also promoting its 600V P7 and 950V PFD7 mosfet as the necessary switches.

Infineon sees LCC as the most resonant topology to follow PFC due to its wide output voltage range, and efficiency up to 94%. “Resonant topologies are usually used for power greater than 100W by most LED driver vendors, where the topology benefits are most prominent, but it can also be deployed down to 40W as an alternative topology to fly-back plus dc-dc buck,” it said.

Find access to the LLC design tool through this web page – using it requires an account to be created with Infineon.

App note: Design of efficient LCC based on ICL5102/HV combo controller IC – which is clearly written and contains a detailed design example.