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PGA309 output voltage

Other Parts Discussed in Thread: PGA309

hello  ti,

           i have design  one PCB board which contain  PGA309,and use this chip to generate voltage .but now one problem  come out,that is  the  PGA309 output  voltage is offen  lost  suddenly  when power  on!!  i donnot  know the reason,could you give me some help?

best  wishes!

    

  • Hello,

    It might be useful if you could provide an oscilloscope screenshot of the power supply of the PGA309 when the part is being powered on. During the supply ramp the PGA309 waits for a valid power supply (>2.2V) and then attempts to read the device configuration from an attached EEPROM. Only if the EEPROM has the proper addresses and checksum values is the output enabled, from the power up section in the datasheet:

  • hello ,
    John, I will get an oscilloscope screenshot when i go to work. this problem is too special. some times PGA309 on my PCB board works well when power on repeatedly. but some times it lost output voltage become zero all the time when power on repeatedly.

    best regards!

  • Yechun,

     

    One other suggestion:

     

    The PGA309 EEPROM should not change after it has been programmed. However, there have been cases where the EEPROM was corrupted during operation. This is normally associated with noisy supplies or environments. The corrupted EEPROM makes the PGA309 non-functional until the EEPROM is re-programmed.

     

    In cases where the EEPROM is corrupted, I recommend that the customer set the OWD bit high (Register 4, bit D15 = 1) when programming is complete.  This bit acts as a write protect function.   I also recommend using a 10k pull-up on the PRG pin of the PGA309.  This helps prevent external noise from affecting the one wire pin.  I think if you implement the recommendation you will eliminate the problem.

     

    Art

  • hello.
    Art,thank you ,i know that it is useful to set the OWD bit high when programming is complete for 3 wire mode. but i used 4 wire mode , i need to set the OWD bit high when using 4 wire mode???

    best regards!
  • The problem is most common for 3 wire mode.  I suppose it could happen in 4 wire mode also; especally if the PRG pin is left floating after the PGA309 has been programed.  You should check the status of the EEPROM after the issue happens.  Is it corrupted?  In general I think setting the OWD = 1 after programing is a good practice for all modes.

    Art

  • hello,
    Art, thank you very much!i will try.but how to set the OWD bit high?i need to set owd bit high at Register Block when i finish calibration under Auto_Cal Block?OR setting when i set Pre-cal file?

    Best regards!
  • Set OWD high in the pre-cal file. The software will set the OWD bit high after calibration.