Original question:
The data sheet says
"Temperature Qualification Voltage – Connect a negative temperature coefficient thermistor. Program temperature window with a resistor divider from REGN to TS to GND. Charge suspends when TS pin is out of range. Recommend 103AT-2 thermistor."
I already have a 2-cell battery with a set thermistor and operating temp range. How do I set this range using the divider at S1?
Hi Mike,
For JEITA Guidelines, an appropriate temperature range for a Li-ion or Li-Poly battery is between 0C and 60C. Using this information, appropriate values for RT1 and RT2 can be derived using the given equation:
The values in the equation are:
-Thermistor resistance (RNTC,T1) at 0C and Thermistor resistance (RNTC,T5) at 60C.
-Expected voltage at TS at 0C (VT1) and expected voltage at TS at 60C (VT5)
VT1 and VT5 are expressed as percentages of REGN:
Given typical values VT1 = 34.375% (0.34275) and VT5 = 73.25% (0.7325)
Solving for RT1 and RT2 will provide the appropriate resistor values for your charger to operate effectively within the JEITA guideline temperature range.
Best Regards,
Juan
