tle4998 Infineon Technologies Corporation, tle4998 Datasheet - Page 7

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

2
To describe the overall temperature dependent behaviour of the IC, we need to consider both the calculated DSP
compensation as well as the natural (physical) temperature behaviour of the Hall probe.
detailed insights in the algorithm that is performed in the TLE4998. Please note that this document treats the
temperature compensation only. The determination of the two parameters GAIN and OFFSET is explained in the
2 point calibration setup document.
Table 1
Internal Value (16bit)
TCAL
OTC
STC1
VALUE1
STC2
VALUE2
STC
HCAL
VALUE
DOUT
The sensitivity
To get a normalized DSP sensitivity
with the junction temperature being expressed as
2.1
All processing in the DSP happens in a deterministic way using integer operation, which has to be kept in mind
when reconstructing its behaviour in a simulation model (Otherwise, when using floating point operations, some
notifiable truncation effects could lead to small inconsistencies between the model and the reality). Nevertheless,
the system is designed in a way that this error should be always less than one LSB for the resulting digital output
value.
Therefore, it is necessary to know that the calculation of one line shown in
and that the results itself are stored in 16bit (signed) integers. All combined “multiply and shift right” operations use
virtually a broader integer width (20bit plus the amount of bits shifted right) due to the employed mechanism in the
processor. When storing a value, a proper saturation is taking place, so that there is no clipping for too big/small
results of any calculation. When passing a value into another equation, a proper sign extension is performed.
User’s Manual
Temperature Coefficient Setup Guide
STC TCAL
S
DSP
(
( )
T
j
=
)
Mathematical Background
Equations performed in the DSP
Influence of the DSP
1
=
+
STC
8192
TL
-------------------------------- -
8 8192
DSP
can then be written as a function of TCAL:
⋅
+
TL
-------------------------------- -
–
160
DSP
8
⎛
⎝
TCAL
--------------- -
–
16
160
Calculation (20bit integer operations)
IFX calibrated (and T dependent) offset value
16T
8192
(
(
(
(
(
(
VALUE
TCAL TCAL
(
TCAL VALUE1
–
(
(
TQ
(
G 16384
TT
HADC
⎛
⎝
S
⎞
⎠
j
TCAL
--------------- -
–
DSP
–
+
+
DSP
DSP
16
768
TQ
--------------------------------- -
(
⋅
⋅
(
1024 8192
(but limited to given CL and CH values)
TL
, the value needs to be normalized by dividing by 8192. We then have
⋅
–
⎞
⎠
DSP
+
VALUE2
(
128
DSP
) HCAL
+
T
OTC
⋅
⋅
j
TQ
--------------------------------- -
–
is calibrated junction temperature in °C)
)VALUE1
) 10
–
128
»
T
DSP
) 11
) STC
160
1024
j
»
⋅
=
) 6
⎛
⎝
) 11
»
TCAL
--------------- -
)TCAL
–
»
TCAL 16
7
16
128
+
) 13
) 8
»
»
STC2
+
⎛
⎝
⎞
⎠
TCAL
--------------- -
(
2
) 7
⁄
OS 16384
+
16
–
»
) 3 ⋅ 1
Temperature Coefficient Setup Guide
STC1
------------------------------ -
32768 8192
+
–
⎞
⎠
TT
»
48
2
–
DSP
.
⋅
TT
----------------- -
32768
) 4
DSP
«
Table 1
⎛
⎝
TCAL
--------------- -
+
⎛
⎝
TCAL
--------------- -
16
32768
16
Mathematical Background
uses 20bit (signed) integers
⎞
⎠
3
⎞
⎠
Table 1
3
.
Rev 1.1, 2008-10-30
gives some more
TLE4998
(1)
(2)