tle4998 Infineon Technologies Corporation, tle4998 Datasheet - Page 13

• Manufacturer Part Number: tle4998
• Description: Programmable Linear Hall Sensor
• Manufacturer: Infineon Technologies Corporation

End Function
The next function calculates the sensor DSP behaviour after precalibration at a given temperature T:
Private Function S_dsppre(ByVal T) As Double
End Function
Finally, there is the calculation function for the DSP polynomial at a temperature T:
Private Function S_dsp(ByVal T) As Double
End Function
For the algorithm we need the already explained error function:
Private Function epsilon(ByVal T) As Double
End Function
4.2.3
The iteration loop looks through all TL_dsp and TQ_dsp values and checks for a best fit (smallest rms error). It is
done in two steps, first it looks for a global optimum with a stepsize of 10 for both parameters. In a second step it
iterates again using stepsize 1 around the global optimum to find a local optimum.
Rem --> Initialize temperature sweep parameters
T_min = -40
T_max = 150
T_step = 10
n = Math.Round((T_max - T_min) / T_step)
Rem --> Initialize variables to keep track of current optimum values
epsilon_rms_opt = 9999
TL_opt = 0
TQ_opt = 0
Rem =========================================================================
Rem --> Sweep in two runs, the coarse global and the fine local search
For Rounds = 1 To 2
User’s Manual
Temperature Coefficient Setup Guide
S_dsppre = 1 + (TL_dsppre - 160) * (T - 48) / 8 / 8192
S_dsp = 1 + (TL_dsp - 160) * (T - 48) / 8 / 8192 +
epsilon = -1 + S_dsp(T) / (Cst * S_dsppre(T) * S_user(T))
Rem =====================================================================
Rem --> Initialize sweep parameters
Rem
If (Rounds = 1) Then
ElseIf (Rounds = 2) Then
TL_lo = 10
TL_hi = 500
TL_step = 10
TQ_lo = 10
TQ_hi = 240
TQ_step = 10
TL_lo = TL_opt - 9
Iteration Loop
First round coarse, second round fine
(TQ_dsp - 128) * ((T - 48) ^ 2) / 1024 / 8192 -
TT_dsp * ((T - 48) ^ 3) / 32768 / 8192
+ (TQ_dsppre - 128) * ((T - 48) ^ 2) / 1024 / 8192
- TT_dsppre * ((T - 48) ^ 3) / 32768 / 8192
TC Setup Part 2 - Calculating the New EEPROM Values
13
Temperature Coefficient Setup Guide
Rev 1.1, 2008-10-30
TLE4998