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Associate
April 7, 2026
Question

L6591 PWM controller

  • April 7, 2026
  • 1 reply
  • 161 views

Hi ST team,

We are going to design variable programable power supply based on PFC + half bridge PWM controller (with fixed transformer turns ratio). Below is the requirement

For Model 1 Vout (Half bridge converter): 3V-63V/5A (180W maximum with auto ranging)

For Model 2 Vout (Half bridge converter): 3V-23V/20A (210W maximum with auto ranging)

PFC output wattage for one channel model: 230W

PFC wattage for second channel model: 460W

 

So could you please suggest can we use the L6563 for PFC and L6591 for our voltage and power application as mentioned above.

 

Regards

Vikram

1 reply

Peter BENSCH
Technical Moderator
April 7, 2026

The boundary parameters of the power supply to be developed are similar to your previous thread, except that you now want to use different devices and, above all, deliver significantly higher maximum power outputs.

If you mean by "auto ranging" max 5A output current and max 180W/210W by reducing the output voltage, then the specifications are technically consistent and in principle achievable with L6563 + L6591 and a resonant half‑bridge.

The wide voltage range of Model 1 (3...63 V) and the high current of Model 2 (up to 20 A) still require a carefully optimised LLC tank, transformer and synchronous rectification, as well as proper CC/CV and power‑limit control.

However, the same conclusion applies here: the discussion of such a design probably concerns only your specific case and goes far beyond the scope of a thread intended for the general public. For detailed questions about the exact implementation, you should therefore contact your local distributor and request support from their FAE resource.

Good luck!
/Peter

VikramHCLAuthor
Associate
April 7, 2026

Hi @Peter BENSCH 

Thanks for update.

You have mentioned resonant half‑bridge here with L6591, but as per datasheet L6591 is half bridge PWM controller so could you please clarify is there need for this resonant half bridge for our application,

Could you please share any reference design link or any calculation sheet for the reference design.

 

Regards

Vikram

 

 

Peter BENSCH
Technical Moderator
April 7, 2026

You are right: the L6591 is specified in the data sheet as a half‑bridge PWM controller with ZVS capability, not as a dedicated LLC resonant controller like the L6599A or L6598D. It can be used in a soft‑switching / ZVS half‑bridge where some resonant behaviour (leakage inductance, added inductors, snubbers) is exploited, but if you are aiming at a true LLC resonant half‑bridge with wide output‑voltage range controlled mainly by frequency, we would normally recommend an LLC‑oriented controller such as L6599A or L6598D.

The only reference design for the L6591 is the EVL6591-90WADP, for which there is also the detailed Application Note AN2852. A calculation sheet would be tailored to a specific application and therefore not universal enough. However, your local distributor should have an FAE for power electronics who can actively support you with your design.

Regards
/Peter