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LM2853 issue

Other Parts Discussed in Thread: LM2852, LM2853

Hello,

Honeywell Pune is using LM2853MH-3.3 in their system. They are in proto stage. They build 25 boards which were working fine. Out of 25 1 board has developed issue on LM2853MH-3.3 device. The output instead of being at 3.3V is varying between 2v to 2.5V even at no load.

This board was working fine initially. Now even if they change the device, inductor, capacitors etc, the board always provide arond 2V output.

We checked the SNS pin connection, Switch node waveform & SS pin connection. All are looking fine.

The only concern I could not was, the team has added an RC filer from PVIN to AVIN. Hence AVIN is lower than PVIN in the begining. They did this as they were planning to use LM2852 before & later moved to LM2853. Being the devices from same family they continued with LM2852 based design.

Please suggest what could be the further steps to debug the same.

Thanks & Regards,

Shridhar More.

  • Hello Shridhar,

    Would you please send us your design schematic? Having a filter on AVIN shouldn't cause that issue. Also the other 24 boards are working fine with the filter at AVIN, am I right? Have you observed the output on the scope? If so, it it oscillating a lot? It could also be a connection issue. Please make sure all the connections are well soldered. You could also try swapping out the IC.

    Regards,
    Akshay