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LP8545: Iset pin and EEPROM

Brian Antheunisse
Expert 5265 points
Part Number: LP8545
Other Parts Discussed in Thread: LP8556, TPS61177, TPS61187

Hi guys,

My customer wants to use the LP8545 but they have a question. They need to enable the Iset pin to set the current threshold, but according to the datasheet the Iset pin is inactive until enabled via EEPROM. However, there is a note about the EEPROM:

"EEPROM NVM can be programmed or read by customer for bench validation. Programming for production devices should be done in TI production test, where appropriate checks will be performed to confirm EEPROM validity. Writing to EEPROM Control register of production devices is not recommended. If special EEPROM configuration is required, please contact the TI Sales Office for availability."

So, can they use a host MCU to adjust settings in EEPROM after the parts boot up? or are they supposed to tell you guys what settings they want and are stuck with them after production test? 

This note is confusing, so some elaboration would be nice on what that means exactly. Is it just that "EEPROM Control Register" with address 72h that is off limits, and the rest of the device settings are fine to change at will?

Thanks,

Brian 

  • 0
    TI__Mastermind 22745 points
    Hi Brian,
    I'm sorry for the late response. As the datasheet says: "Writing to EEPROM Control register of production devices is not recommended. ". That means it's not suggest for customer to use a MCU adjust setting in EEPROM. But you can connect sales to confirm whether TI can provide and test special EEPRM setting for customer.
    Another thing is that this device is a very old device. could you recommend like LP8556, TPS61187,TPS61177 for your customer. Maybe that is more suitable. Or could you provide your customer's requirement and application. I can help you to choose right part.
    Sean
  • 0 in reply to Sean Zhou
    TI__Expert 5265 points

    Sean, 

    Sorry, but your answer doesnt really clear anything up. You are saying that the EEPROM is only supposed to be programmed once, by TI, during production? And the custom settings will remain there forever, even between power cycles?

    They already have a prototype with this part, so while there still is time to change it, I only want to recommend that if it is completely necessary. If the answer to my above question is "yes," then ok I will recommend the other devices. 

    Thanks,

    Brian 

  • 0 in reply to Brian Antheunisse
    TI__Mastermind 22745 points
    Hi Brian,
    Yes, the EEPROM is supposed to be programmed by TI during production. When it power on, the device will read the default setting in EEPROM(TI Programmed during production).
    Can you tell me why your customer want to change the setting in EEPROM? I suggest your customer to setting the register every time when it power on with a MCU. I have some other customers, although the default setting in EEPROM is not what they need, the will rewrite the registers when it power on. Because you already have MCU, so I think it's very easy to set the register every time when it power on. Do my understand is right?
    Sean
  • 0 in reply to Sean Zhou
    TI__Expert 5265 points

    Sean,

    Yes, they have an MCU sitting next to their LP8545. I have to say, I am pretty confused by your comments.  

    Is it recommended by TI to use an MCU to adjust register settings within this part's EEPROM, or is it not recommended and they should choose another LED Driver?

    Thanks,

    Brian

  • 0 in reply to Brian Antheunisse
    TI__Mastermind 22745 points
    Hi Brian,
    I'm sorry for confusing you. For you application with a MCU, it's ok to use an MCU to adjust the EEPROM.
    Every time you power on the device, you need to use MCU to write the setting registers.
    Sean