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BQ77PL900: BQ77PL900 EEPROM programming error

Mete Yasan
Intellectual 500 points
Part Number: BQ77PL900

Hi,

The customer has designed their own board with using BQ77PL900, which is very similar to the EVM in schematic design. 

They try to program the EEPROM with using the GUI and EV2300. But, they get the errror on the GUI: "EEPROM did not program correctly." during programing process, although they can write to all registers without any problem. 

They have applied PACK + and PACK- 20V and more. However, they just get Vgood during programming, but after they get the programming error, Vgood is disabled. 

Do you have any recommendation to solve this problem?

Regards,

Mete

  • 0
    TI__Guru 54715 points
    Hi Mete,
    Be sure the VOUT signal from the EV2300 reaches the EEPROM pin of the bq77PL900, preferably level shifted to the VLOG voltage if necessary. Also confirm that the supply voltage does not drop out during programming. If programming at the board level connecting both BAT+ and PACK+ to 20V is recommended keeping all cell voltages in a safe range. VGOOD should come on and go off during the programming process.
  • 0 in reply to WM5295
    Intellectual 500 points

    Hi WM5295,

    Thanks for your suggestions. The Vout is measured 0.45V when no programming condition. when the programming begins, it goes up to 5V. after receiving error, it gows down to 0.45V again. 

    No drop out is observed on the supply voltage. 

    So, I think we need more. 

    Thanks,

    Mete

  • 0 in reply to Mete Yasan
    TI__Guru 54715 points
    Hi Mete,
    The programming flowchart from the data sheet or a working variation of it is built into the GUI software, but could be influenced by the PC and EV2300 used. (The GUI software likely does not read back the registers as indicated in the flowchart since it would have just written them. ) It seems communication to the part is OK and the VOUT will toggle. The VGOOD status appears and goes away and the VOUT is turned off so the sequence seems to complete.
    From the PC side the language and regional settings can sometimes influence GUI operation, in some cases setting english and "US" in the PC settings can influence a software, but again software appears to be working from your description. In some cases newer operating systems have displayed text boxes as black and using a classic windows setting is helpful, but this does not seem to be the reported issue.
    From the hardware side the appropriate signals must get to the IC. I2C apparently works as data can be written and read. VOUT must reach the EEPROM pin, if VLOG is 3.3V the EEPROM level should be dropped or it will pull up the supply. Power must be adequate or programming will not work. Note in the block diagram that regulators come from CPOUT. CPOUT must remain in the 15-20V range during programming. In the past problems have been reported when trying to program with 22-30V applied to BAT or PACK although it remains steady during programming. You mention "20V and more", this may be a good thing to check.