I am analyzing a buck regulator circuit as shown in following figure.

Buck regulator using AOZ1014

link for datasheet given here: http://aosmd.com/pdfs/datasheet/AOZ1014AI.pdf

I have few queries in schematic:

Q1. In above schematic, IC U16 is getting burned unexpectedly by getting hot. Can someone suggest me the solution? Is there any flaw in design?

Q2.Why two inductors are connected here, because in datasheet and standard buck regulator, there is only one inductor.

Please suggest, how can prevent IC from burning and malfunctioning ? Thanks in advance. :)

PS. "Lamp" signal to EN pin is coming from Microprocessor (5V). & Vin is 12 V DC.

  • 1
    \$\begingroup\$ L4 is part of the output filter, along with the four capacitors C45-48. It's not taking part in the "buck" circuit. L3, D22 and U16 are the buck section. \$\endgroup\$ – John Honniball Nov 6 '14 at 14:25
  • \$\begingroup\$ What current does your load draw? The circuit could be completely correct, but drawing too much current would cause the IC to heat up. \$\endgroup\$ – LeoR Nov 6 '14 at 14:51
  • \$\begingroup\$ When you write that Vin is 12V DC - have you measured that, or do you assume that based on the rating of your transformer? \$\endgroup\$ – brhans Nov 6 '14 at 15:16
  • \$\begingroup\$ The part claims to have cycle-by-cycle current limit and thermal shutdown. So maybe the input voltage is spiking too high? Input line transients? It's also marked as not suitable for new designs so it may have issues. \$\endgroup\$ – John D Nov 6 '14 at 15:23
  • \$\begingroup\$ You should also check the switch node to see if there's any excessive ringing. \$\endgroup\$ – John D Nov 6 '14 at 15:30

From the dataset, the AOZ1014 has a Vin range from 4.5V to 16V. make sure that your Vin is in this range. But the AOZ1014 has some protection features like an OCP to protect your circuit from over current by comparing the voltage of the COMP pin which is proportional to the peak inductor current and shut down your circuit is case of overcurrent, make sure that you use the appropriate values of RC and Cc.

  • \$\begingroup\$ Is there can be problem in transformer and rectifier from where we are getting Vin to AOZ1014, like spikes in ac voltage which is reflecting ripple in Vin signal? \$\endgroup\$ – Techknowlogic Nov 6 '14 at 16:10

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