L6591 PWM controller

[VikramHCL]

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

[Peter BENSCH]

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

[VikramHCL]

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]

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

[VikramHCL]

Hi @Peter BENSCH ,

Thanks for the clarification.

Could you please help here to understand which IC / topology (L6591D or L6598D) will be best suitable for our application of programable PSU design (wide output voltage range & output power requirement).

Regards

Vikram

[Peter BENSCH]

For a programmable PSU with wide output voltage range and power limit control, L6598D is generally the better fit than L6591D.

• L6598D is an LLC / resonant half‑bridge controller, so it is better suited to wide output voltage regulation by frequency modulation. This is the most natural choice for a programmable isolated PSU with a broad Vout range and auto‑ranging power/current limits.
• L6591D is a half‑bridge PWM controller with ZVS capability. It can support soft‑switching half‑bridge designs, but it is not the most direct choice for a true LLC-style programmable PSU with a wide output range.

If your target is true wide-range programmable output voltage, use L6598D.
If your goal is a simpler soft-switching half‑bridge with less demanding output range requirements, L6591D may be considered, but it is not the preferred option here.

Regards
/Peter