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Question for TPS65175 VCOM write/read

Eric Kim1
Prodigy 170 points
Other Parts Discussed in Thread: TPS65175

 Hi Team,

LG Display was informed that Panasonic encountered the reading problem of  VCOM with Panasonic system board.

 

1.Background :

 

LG Display provided the LG Display panel board and Panasonic mounted TPS65175 in his TV main board, it is named as Open Cell business in LG Display.

 

To calibrate the VCOM, Panasonic writes the VCOM data on TPS65175 and vilifies the VCOM data.

 

It seems that Panasonic is under development state of 32” TV model.

 

2.Problem :

 

Panasonic read the  VCOM digital data after writing the VCOM data, but the read data is different from written VCOM data.

 

However, the  read VCOM data is same as the written VCOM data after system off and on.

 

 

The attached file provided from Panasonic :

 customer information.pptx

3.LG Display question for the VCOM Data writing :

 

LG Display understand the written VCOM data will be stored in register and EEPROM of TPS65175 but is there any possibility to be stored of wrong VCOM data only register when writing data in TPS65175?

 

It seems that the written VCOM data is stored successfully in EEPROM, as the read data of VCOM is correct when power off and on was done.

 

 

 

4.Eric’s opinion:

The read VCOM data is 000 and before data is also 000.

Could this phenomenon be occurred if the I2C communication had a problem during VCOM data reading though the written VCOM data was successfully stored in register and EEPROM both.

 

 

Thanks and regards,

  • 0
    TI__Expert 8010 points
    Hello Eric,

    What is the time between writing on the EEPROM and reading out of it? You need to be aware of the dead time of 50 ms. During this time all the register data are stored into the non volatile EEPROM cell and during this time there should be no data flowing through the bus. If you refer to read out data, do you mean you read the DAC or the EEPROM?

    Is it possible to get the I2C protocol that means the responding address/data of the command for the VCOM change?

    I understand that it seems that the data are stored correctly in EEPROM because of the power on/off cycle. What I suspect is when you first write into EEPROM register but you read out the DAC Register...

    Thank you.
    Best Regards,
    Ilona