DC-DC convertor 5v/3A paralel connection

Hi
Am using 3A Dc-Dc converter which is driving from 24v DC and converting to 5v/3A DC , am using same circuit what they have suggested , single module can handle 5V/3a , in order to get 5V/9A i have connected 3 DC-DC converter parallel , but some times any one of the IC is getting heated and after some days getting damage ,

Lm2576 -5v

if am going to use 3 nos of LT3976 [3A/5V] instead of 3Nos of LM2576 [3A/5V] , will it solve the issue?

What is the main difference b/W switching regulator and DC-DC converter , how it will help for parallel connection , i think both are same . right?

Paralleling of DC DC converters is very much possible. But to do this, one need to understand the intricacies of the DC DC converter, paralleling them, load sharing, load balancing and failure conditions (these will be in tons ).
There are readily availabe DC DC converters with feature of Droop compensation. These can be directly used for paralleling of the converters without any extra protection circuits.

But you need to select the number of converters in a way considering worst case max load current and allowing a safer load current margin for each converter. So if you need 9A load current and using 3A individual converters, then you have to use 4 such converters for a better and safer power module.

Below are the links which gives you more information on this and some example modules.

https://www.ti.com/lit/an/slva060/slva060.pdf
https://www.ti.com/lit/an/slva250/slva250.pdf
https://www.digikey.com/en/articles...-dcdc-modules-to-generate-higher-output-power

If you are using a regulator then use diodes at the outputs.
https://www.wallindustries.com/docs/appnotes/Parallel_Operation_Of_DC_Power_Modules_AN.pdf

there are lot's of DC-DC converters or Controllers available from TI,Linear,Maxim,Intersil,Onsemi etc. which can give 9A like MIC26903YJL,RT7259GQW,MIC261203YJL . Paralleling may not be good IDEA for 9A
.

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We can increase the input voltage range of converters also.
see this