ADP1031-2 working in PSM mode

In our product ADP1031 sometimes switches to Power Saving Mode PSM (with skipping pulses). In this case, everything works, but there is an interference at a frequency of ~7 kHz (Fsync = 512kHz/72), which falls into the band of the measuring chain of the product. This interference degrades the parameters of our device to unacceptable levels. How can we avoid the swithing ADP1031 to PSM mode?

Best Regards,

Alexander

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  • 0
    •  Analog Employees 
    on Apr 1, 2021 2:45 PM

    Hi Alexander, 

    The ADP1031 automatically switch to PSM mode for light load conditions for all three regulators. PSM is inherent to the ADP103x and this mode cannot be turned off but to prevent the part going into PSM mode, a solution is to add a dummy load of few mA's for the part to operate at DCM. This will add a power dissipation but this will prevent the low frequency switching that cause the interference to the band of interest. 

    Best regards, 

    Jefferson 

  • Hi Jefferson,

    It could be a good solution. But tell please where is it better to connect the load?

  • 0
    •  Analog Employees 
    on Apr 4, 2021 3:08 PM in reply to alex.bukvin@teson.com.ru

    Hi Alexander, 

    It would be good for us to know which of the three regulators is running in PSM mode in the applications condition where the interference was seen. You can use the scope and probe on each of the output of the regulator. Then, add a dummy load of few mA's (increasing from uA to mA range) on the regulator operating in PSM mode for it to go  into DCM. You can double check on the final output if there still interference.

    Thanks and regards, 

    Jefferson 

Reply
  • 0
    •  Analog Employees 
    on Apr 4, 2021 3:08 PM in reply to alex.bukvin@teson.com.ru

    Hi Alexander, 

    It would be good for us to know which of the three regulators is running in PSM mode in the applications condition where the interference was seen. You can use the scope and probe on each of the output of the regulator. Then, add a dummy load of few mA's (increasing from uA to mA range) on the regulator operating in PSM mode for it to go  into DCM. You can double check on the final output if there still interference.

    Thanks and regards, 

    Jefferson 

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