LTM4622A parallel combination issue

Question

Dear Sir/Mam, 
 Please find the attached schematic for your reference. 
 Input Voltage: 16VDC 
 Output Voltage Required: 12VDC/4A 
 I have designed a schematic as per figure No: 28 in the LTM4622A datasheet. 
 But when I connect the input supply, it get burned. 
 Please let me know if I am doing anything wrong. 
 Thanks in advance. 
 
 PDF

MarkusHP · Answer

Hello Akarsh, 
 if part gets burn at start-up/connecting input supply: please see following document: 
 https://www.analog.com/media/en/technical-documentation/application-notes/an88f.pdf 
 Regarding the desired 12V@4A output load: Figure 29 is a better example for such high output voltages, but figure 28 fits in principle as well. 
 And please start using common sense on power numbers: 
 12V*4A are 48W! 
 Even with very good 94% efficiency you end up with 3W power losses in the tiny modul! Please check the derating curves and thermal impedance in the datasheet to get a number for maximum ambient temperature or possible reduced output current capability. 
 
 kind reagrds 
 Markus

MarkusHP · Answer

Hello Akarsh, 
 as stated above the AN 88 describes a possible scenario where a DC/DC regulator gets burned/destroyed by voltage transients at the input. Please try following: 'turn-on'/connect the Agilent DC supply at 0V and increase input voltage manually resp. slowly till the desired input voltage. If your circuit survives this test I bet AN88 will offer you a solution. 
 kind regards 
 Markus