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bq77PL900 - EEPROM programming issue

Rob Mitrunen
Expert 1685 points
Other Parts Discussed in Thread: BQ77PL900

My customer just designed a board with bq77PL900 for 5 cell series protection cct, but ran into a problem programing the EEPROM on the bq77pl900.
When they try and program the EEPROM with the EV2300, they get the error message "bq77PL900: VGOOD did not get set. EEPROM programming cancelled."
Note the pack voltage is at 20V and VLOG is set to 5V. Suggestions?

  • 0
    TI__Guru 54715 points

    The most probable cause is that the 20V is not getting to the part. VGOOD will be set if the device has adequate power supply and the proper communications are received. The program must also be able to read the status to continue the programming sequence.

    Be sure the supply does not current limit and check that the 20V is present at the PACK pin during the programming sequence. If the board is isolated, the same voltage can be applied to both the battery and pack side of the board.  If cells are attached or the fixture loads the battery side, set the part to host mode with the FETs off.

    Also check for intermittant communications. This might show up as an error status in the GUI window or may need inspection of the bus activity.

    The user might also confirm the EEPROM signal is present at the device, although this should not cause the VGOOD error.

    If the error occurs on one board only, it may be a damaged board or device. If all boards, it may be a test setup or board design issue.

  • 0 in reply to WM5295
    Expert 1685 points

     

    The customer still has the same error and cannot program the EEPROM. They checked the voltage on pin 47 (PACK) and there is 20V. The board is used in stand alone mode.

    The problem  programming the EEPROM occurs on more than one of the customers designed board.

    They had two boards build and they both have the same problem. The customer says the design is the same as the EVAL schematic.

    They can program the EEProm on the BQ77PL900EVM-001 board. Any suggestions what to check next?

     

  • 0 in reply to Rob Mitrunen
    TI__Guru 54715 points

    The eval board had several options for grounding. Be sure one is implemented and a good connection exists between the device ground and the supply negative. Check. that there is no offset between the power supply and the device ground. Perhaps the device has enough voltage to communicate but insufficient to program. Unexpected offsets can develop in a fixture.

    Since the user has a working and non-working system, comparison measurements between the 2 should find a difference.

    Use the same data file for programming between the 2 boards. One community member seemed to indicate a data dependency, but this was apparently resolved.  Note the recommended write limit in the data sheet, a part with many writes used in development may not be best for long term data retention.

     

     

  • 0
    Prodigy 30 points

    I had this same problem.  My problem was that the chip wasn't getting power; everything was hooked up, but i wasn't getting anything on either the 3.3V or 5V pins.  It turns out that, in orde to "turn on" the board, you need to have a load connected to the "Pack" headers, and then after that you have to short the positive "Batt" header to the positive "Pack" header momentarily.  It will spark when you do it, but the data sheet says to do it and it really does work.