I am using MCP73833 which has the following datasheet https://ww1.microchip.com/downloads/en/DeviceDoc/22005a.pdf
They says that "An internal 50 μA current source provides the bias for most common 10 kΩ negative-temperature coefficient thermistors (NTC). The MCP73833/4 compares the voltage at the THERM pin to factory set thersholds of 1.20V and 0.25V, typically"
For example, by utilizing a 10 kΩ at 25C NTC thermistor with a sensitivity index, β, of 3892, the charge temperature range can be set to 0C - 50C by placing a 1.54 kΩ resistor in series (RT1), and a 69.8 kΩ resistor in parallel (RT2) with the thermistor as depicted in Figure 6-1.
Now I just can't figure out how to properly calculate the resistors required series/parallel with NTC for desired window set, a more generic way based on RHOT and RCOLD (ie. for other range)
The best I came up with and I am stuck. Appreciate a little help.
1 1 1 ---- = ------ + -------- 24-RT1 RT2 rcold 1 1 1 ---- = ------ + -------- 5-RT1 RT2 rhot