LLC Resonant mode Controller
Increasing efficiency with resonant mode power supplies
What is a resonant mode controller IC?
Resonant mode power supplies are a variation of switched-mode power supply (SMPS) circuits offering a number of advantages such as high efficiency, low EMI, and high power density. By applying ZCS (zero-current) and ZVS (zero-voltage) switching schemes, switching losses are reduced significantly. Consequently, these resonant converters are also known as soft-switching controllers. Non-resonant mode SMPS circuits rely on hard-switching techniques. As such, Infineon offers 2 types of resonant mode controller ICs, namely hybrid flyback (or commonly known as asymmetric half-bridge flyback topology) and LLC controllers.
Both types of resonant controllers share similarities such as utilizing an external capacitor as well as leakage inductance from the main transformer to form a resonant tank to aid its switching operation. Although both types of converters look similar at first glance, distinct differences exist to best fit each targeted application. >Selection guide
Hybrid flyback controllers combine the simplicity of a flyback with the performance of resonant mode. By utilizing two high-voltage MOSFETs such as CoolMOS™, hybrid flyback controllers are able to drive both high-and low-side MOSFET in an asymmetric half-bridge flyback topology. To reduce switching losses, ZVS and ZCS are achieved through the means of regulating both positive and negative magnetizing current. In addition, transformer leakage energy is recycled thereby further reduces switching losses.
| HFB | LLC | |
| Wide range input | Yes | No |
| Rectification at secondary side |
Single diode or SR MOSFET | Dual diode or SR MOSFET |
| Breakdown voltage of SR MOSFET |
>= 150 V | >= 40 V for 12 V output voltage |
| Recommended power range | < 200 W | > 150 W |
| Recommended design | Single output with variable Vout | Single or multiple output with fixed Vout |
| Target application | USB-PD charger | SMPS for audio, TV, PC, Server and industrial power supply |
Best-in-class converters to support LLC HB resonant mode topology
ICE1HS01G-1 resonant mode converter, housed in a DSO-8 package, is an easy-to-design component to realise a LLC HB resonant application. An oscillator is built-in allowing designers to set the suitable operation frequency range with a resistor. In addition, ICE1HS01G-1 offers a programmed soft-start function to limit both the inrush current and the overshoot in output voltage. To protect the system during operation, mains input under-voltage protection and over-current protection are also in-built. Hence, it is able to operate in resonant mode with the highest reliability possible.
ICE2HS01G is a high performance resonant mode controller designed especially for high efficiency half-bridge or full-bridge LLC resonant converter with synchronous rectification at the secondary side. With its new driving techniques, the synchronous rectification can be realized for LLC converter operated with secondary switching current in both CCM and DCM conditions. No special synchronous rectification controller IC is needed at the secondary side. The maximum switching frequency is supported up to 1MHz.
Except the patented SR driving techniques, this IC provides very flexible design and integrates full protection functions as well. It is adjustable for maximum/minimum switching frequency, soft-start time and frequency, dead time between primary switches, turn-on and turn-off delay for secondary SR MOSFETs. The integrated protections include input voltage brownout, primary three-levels over current, secondary over load protection and no-load regulation.
