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My requirement is as follows:

  1. Input Supply 110+-30% VDC i.e., 77VDC to 138VDC.
  2. output need to be 24VDC 5A.
  3. All the basic protections like short circuit, Reverse polarity.
  4. No power consumption when no load.
  5. Rugged design to sustain harsh climatic condition.

I have thought to use Half Bridge LLC topology. using infenion IC IRS27952.

Suggest me better high Efficiency topology or another equivalent Transistor drive IC that can surve my purpose.

Md Adil
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    I couldn't find any LLC controllers with the name IRFB27952 (Actually I found nothing). Could you please link the datasheet to the actual part? – Rohat Kılıç May 20 '21 at 08:44
  • Sorry My mistake ..... It was IRS27952. https://www.infineon.com/dgdl/irs27951s.pdf?fileId=5546d462533600a40153567b77792849 – Md Adil May 20 '21 at 09:05
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    "*No power consumption when no load.*" Not possible. There will have to be some quiescent power. – Transistor May 20 '21 at 13:29

1 Answers1

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This may help to select topology based on power levels.

  1. All the basic protections like short circuit, Reverse polarity.

Protection against input voltage with reverse polarity is independent of the converter's topology. You can build a simple reverse polarity protection with a MOSFET (ideally, PMOS) and a few passive components. However, if you want something like "protection against applying voltage from output-side with even reverse polarity" don't laugh, you can see such requirements in automotive then things may change.

  1. No power consumption when no load.

There's no such thing as "no power consumption at no-load". There should be some acceptable power levels. For example, EU 2019/1782 ANNEX II defines the maximum allowed power consumptions for different power output levels (including no-load). So you should explicitly specify the no-load power consumption.

Anyway, here are my thoughts:

  • LLC converters are a bit problematic at no-load regulation. So I'd not go for LLC. But if the controller has some magic inside for no-load regulation then LLC may be an option.

  • Flyback could be another option. But flybacks are terrible in terms of EMC performance. Though you didn't specify any EMC requirements so I don't want to say anything extra about this.

  • I'd go for either two-switch or active clamp forward converter.

Rohat Kılıç
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  • Thanks for the response. 1. I need the short circuit and reverse polarity protection for load only. well i will manage that. battery chargers are the examples where there comes power supply from external sources. 2. No to low power consumption is required. 3. Power supply shall be EMI/EMC compliance. 4. Also can you brief Two switch / active clamp forward convertor. – Md Adil May 20 '21 at 09:15
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    `2. No to low power consumption is required.` This is meaningless. Use numbers. 100mW? 10mW? 50mW? You should specify the **exact value**. This is important because this will tell you if you can use a standby regulator for control and, for example, active cooling devices (if necessary). `Also can you brief Two switch / active clamp forward convertor.` There are tons of online documentation. For specific controller ICs there are even reference designs. – Rohat Kılıç May 20 '21 at 12:01
  • @MdAdil, "*I need the short circuit and reverse polarity protection for load only.*" A power supply can't give reverse polarity protection for the load. Only the load can do that. The best the PSU can do is limit the current. – Transistor May 20 '21 at 13:32
  • @RohatKılıç Thanks for the help. I will be using (Low Side) Active Clamp Forward Convertor. I will use a combination of LT3752 + LT8311. The LT3752 is current mode PWM controllers optimized for an active clamp forward converter topology. The LT8311 is used on the secondary side of a forward converter to provide synchronous MOSFET control and output voltage feedback through an opto-coupler. – Md Adil May 20 '21 at 13:58
  • @Transistor, I got it. – Md Adil May 20 '21 at 14:07
  • If my answer is satisfactory and helpful enough then you can accept it so that the question does not remain open. – Rohat Kılıç May 20 '21 at 16:36