TLE4997 Datasheet, PDF (27/36 Pages) Infineon Technologies AG – Programmable Linear Hall Sensor for Industrial Use

TLE4997I
Temperature Compensation
8
Temperature Compensation
The magnetic field strength of a magnet depends on the temperature. This material
constant is specific to different magnet types. Therefore, the TLE4997I offers a second
order temperature compensation polynomial, by which the Hall signal output is multiplied
in the DSP.
There are three parameters for the compensation:
• Reference temperature T₀
• A linear part (1^st order) TC₁
• A quadratic part (2^nd order) TC₂
The following formula describes the sensitivity dependent on the temperature in relation
to the sensitivity at the reference temperature T₀:
S_TC(T) = 1 + TC₁ × (T – T₀) + TC₂ × (T – T₀)²
For more information, see also the signal processing flow in Figure 5.
The full temperature compensation of the complete system is done in three steps:
1. Pre-calibration in the Infineon final test.
The parameters TC1, TC2, T0 are set to maximally flat temperature characteristics
regarding the Hall probe and internal analog processing parts in the 100 mT range.
2. Overall System calibration.
The typical coefficients TC1, TC2, T0 of the magnetic circuitry are programmed. This
can be done deterministically, as the algorithm of the DSP is fully reproducible. The
final settings of the TC1, TC2, T0 values are relative to the pre-calibrated values.
Table 16 Temperature Compensation
Parameter
Symbol Limit Values Unit
Notes
min. max.
Register size TC₁
TL
1^st order coefficient TC₁ TC₁
-
9
bit
Unsigned integer values
-1000 2500 ppm/ °C
Quantization steps of TC₁ ∆TC₁
15.26 ppm/ °C
Register size TC₂
TQ
2^nd order coefficient TC₂ TC₂
-
8
-4 4
bit
Unsigned integer values
ppm/ °C²
Quantization steps of TC₂ ∆TC₂
0.119 ppm/ °C²
Register size T₀
TR
-
3
bit
Unsigned integer values
Reference temperature T₀
- 48 64 °C
Quantization steps of T₀ ∆T₀
16
°C
1)
1) _{A quantization step of 1°C is handled by algorithm (See Application Note).}
Data Sheet
27
V 1.0, 2007-06