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LT8490/LT8491_configuration_algorithm

Hello,

In a datasheet of LT8490 and LT8491 buck-boost controller is written that value greater than 25mR for Rsense1 resistor is not recommended. What is the reason for that? What could happen if 27mR or 30mR resistor as Rsense1 is chosen?
What is the period of full panel scan hardcoded in LT8490? According to graphs, it is arround 180 s, but is it exactly 180 s or more/less?
Regarding to LT8491 controller - is it possible trig a full panel scanning for global maximum power point manually (over I2C) or is possible just to set a period of automatical scanning (register address 0x4C)?
Imagine that period of scanning is 30 s. 10 s after last scan a period is changed to 60 s. When will first next full scan scan happen - at the same time when period is changed or 60 s later (70 s after previous scan)?
What is the tracking frequency of P&O algorithm integrated in LT8490/LT8491 controller?

Many many thanks!
Best regards.

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  • Hi Dh159,

    1. The Rsense value minimum is not a hard number. As the resistor value increases, noise and pin leakages start to have an effect.
    2. On the LT8490, the nominal scan time is 183 seconds but could be significantly different at times based on what the software is doing.
    3. There is no direct way to invoke a full scan manually. It will do a full panel scan on start up.
    4. Configuration changes can only be done when the LT8491 is disabled. See “EEPROM: Writing” on page 25 of the datasheet.
    5. Local maximum is determined and adjusted roughly every 0.5 seconds.

Reply
  • Hi Dh159,

    1. The Rsense value minimum is not a hard number. As the resistor value increases, noise and pin leakages start to have an effect.
    2. On the LT8490, the nominal scan time is 183 seconds but could be significantly different at times based on what the software is doing.
    3. There is no direct way to invoke a full scan manually. It will do a full panel scan on start up.
    4. Configuration changes can only be done when the LT8491 is disabled. See “EEPROM: Writing” on page 25 of the datasheet.
    5. Local maximum is determined and adjusted roughly every 0.5 seconds.

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