Want to design DCDC converter using L6462A IC

[Nayeem]

Hi,

 

I want to design a 600 W converter which should work during power shut down 190 V to 60 V input and output voltage will be 300 V. Switching frequency 150 kHz to 190 kHz. Want to use L6462A IC as there is a evel board which perform the same (ACDC  -- PN: EVL6462A-250W-M). 

Operation time = 100 msec.

I also need an enable signal to turn on the DCDC converter.

Please let me help to design the schematic and are we able to use L6462A IC for the application.

 

Additional Information:

1. Topology is already selected and simulation is done. --- Non isolated boost converter.
2. L6462A is ok to use? ST already build an eval board as PFC. Can anyone provide me the schematics or suggestion for the DCDC converter.
3. Peak current controller is fine.
4. I also want to mention that we already build the dcdc converter with TI28379D microcontroller. Reason to use the IC (L6462A or else) because we want to bypass the software coding.

[Nayeem]

Any technical reply will be helpful.

Thanks.

[ozammo]

Hi Nayeem,

 

Would you be able to provide further clarity on what you are specifically asking for, as you are stating that your simulation has done. Does this mean your topology is working as expected but you would like additional confirmation that the L6462A  is suitable for use? Having a look at the datasheet and the eval board I do not see why not, I have not used this chip but thats as much information as I can give without looking at a schematic. Are you comfortable with PCB design?

[Peter BENSCH]

Welcome ​@Nayeem, to the community!

The L6462A may be usable in principle as an analogue peak-current-mode controller for a non-isolated boost converter, but it should not be assumed suitable only because the EVL6462A board exists - that board is a PFC reference and is not a direct validation for a 600W DC/DC design.

The L6462A does not use a fixed oscillator to set a constant switching frequency. Its switching frequency is mainly determined by transition-mode operation, zero-current detection, and valley switching/valley skipping, so it varies with input voltage, load, and inductance.

So for your application, the frequency will be operating-point dependent, not fixed at 150…190kHz. The resulting switching frequency may well be only some tens of kHz, which means stable operation within your input voltage range is questionable, especially at the lower desired limit of 60V DC, which would result in peak currents in the boost inductor of around 20A or more.

Perhaps L4984D or L4985 are more suitable candidates, although it would still need to be checked whether the lower input voltage of 60 V can still be handled sensibly - at least I do not have any reliable information on this.

Good luck!

Regards
/Peter

[Nayeem]

​@Peter BENSCH  Thanks for your quick reply.  As I mentioned early it is just for 50 msec hold up when the system shut down. for that time capacitors size become huge and we cannot use the electrolytic capacitors. And then I come up with a baby booster concept like TI present for their 1kW PFC design. That is why I consider avg current 8A with 300uH inductor. not considering 20A and also not worried about thermal or inductor saturation and more ripples. I just want to sustain the output voltage up to the hold up time with compact design. 

I will check L4984D datasheet.

Please let me know if you have any other concerns.