LT3650-8.2

NTC function is described in the datasheet as follows.

would you teach how LTC3650 detect NTC pin unconnected. what is the threshold voltage to detect unconnected during sourcing 50uA?

How large additional resistor can I add to NTC pin to increase the effective temperature threshold?

---- description in the datasheet -----------------------------------------------------

If the NTC function is not desired, leave the pin unconnected.

The NTC pin sources 50µA, and monitors the voltage dropped across the 10kΩ thermistor.

If higher operational charging temperatures are desired, the temperature range can be expanded by adding series resistance to the 10k NTC resistor.

Adding a 0.91k resistor will increase the effective temperature threshold to 45°C.

  • 0
    •  Analog Employees 
    on Dec 17, 2020 10:46 PM

    Hello,

    This is given in the spec table in terms of impedance:

    As low as 250kOhms on the NTC input will disable the NTC function.

    Take a look at this tool which may help you to create an appropriate thermistor network for your needs. Adding more than a few hundred ohms of series resistance to the thermistor will severely skew the temperature profile, but maybe that's what you want.

    XLSX

    Regards,

    Zack