B-constant(B-value) is a tendency for resistance in temperature change,also say
it's the curve for temperature and resistance change, i.e. Counted on 2 resistance
values at each 2 different temperature points,
the formula as follow:
R1:Resistance in ohms at temperature T1
R2:Resistance in ohms at temperature T2
T1=273.15k +( T1℃), T2=273.15k+ (T2℃)
Their relation made a curve, we call R-T curve.
B-constant(B-value) is between 2000~6000K, and it is relative with resistance,
low resistance low B-constant, high resistance high B-constant.
Their curve is very smooth.
Normally B-constant at 25/50C, 25/85C,0/100C,0/50C, we can provide the
customizing or specials.
B-constant is not suit for all thermistors, if the NTC thermistor only control in one
temperature point, no matter how change for the B-value, not important for it;
if the thermistor must control several temperature points, B-constant is very
important for it, he will design the resistance how to change.
The more high accuracy the more difficult to control, it can control in a little temperature
range, normally is 20-40 degrees. Cause the resistance has its tolerance, and so does
the B-value, their tolerance will compose like a two-ways bell-mouthed, the accuracy will
extend from the centre to both sides.
In the curve, B-constant like controller, and resistance like executor, B-value will design
resistance's tendency in temperature change.
When the thermistors need the B-constant are same, it can use any resistances.
E.g. B25/50=3950, R25 can be 10kohms, 20kohms, 30kohms or other, no matter the
resistance changed, its curves are the same.
Same B-constant, different Resistance
When the thermistors need the resistance are same, it can use any B-constant.
E.g. R25=10Kkohms, no matter the what B-constant, the thermistor need it is 10kohms
at 25C, its curves are at overlay point only.
Different B-constant, Same Resistance