Infineon Technologies TLE5012B - Calculation of the Junction Temperature; Calculation of the Temperature

TLE5012B
Specification
User’s Manual 27 Rev. 1.2, 2018-02
4.3 Calculation of the Junction Temperature
The total power dissipation P
TOT
of the chip leads to self-heating, which increases the junction temperature T
J
above the ambient temperature.
The power multiplied by the total thermal resistance R
thJA
(junction to ambient) yields the junction temperature.
R
thJA
is the sum of the two components Junction to Case and Case to Ambient.
(4.2)
Example (assuming no load on V
out
):
(4.3)
4.4 Calculation of the Temperature
The TLE5012B provides the temperature in the TEMPER bits of the FSYNC register via the SSC interface (see
Chapter 6.2) or with an extended SPC frame (see Table 5-8). TEMPER is a compensated value of the
temperature at the ADC. The compensation is done with an offset value at 25°C temperature (T25O), which is
specific for each device. The T25O value is measured for each device during production and it is stored in the
fuses.
The temperature in degrees Celsius (°C) can be calculated using the formula provided in Chapter 6.2 and reading
the TEMPER bits. TEMPER is a signed register, to convert the value to digits proceed as described in
Chapter 6.1.3. As an example, for a TEMPER value of 110111000
B
, the value in digits is calculated in
Equation (4.4):
(4.4)
Therefore, the temperature in degrees Celsius is calculated in Equation (4.5):
(4.5)
TEMPER typical accuracy error is around +/-5°C across the whole temperature range.
TEMPER is a limited register. For a whole temperature range use the T_RAW register, which can be compensated
with the T25O register. The relation between TEMPER and T_RAW is shown in Equation (4.6):
(4.6)
)(
∑
×+××=×=Δ
Δ+=
+=
Q
QQDDDDthJATOTthJA
AJ
thCAthJCthJA
IVIVRPRT
TTT
RRR
(I
DD
, I
Q
> 0, if direction is into IC)
[] [] [ ]
()
KVAAV
W
K
T
mAI
VV
DD
DD
5.100014.05150
14
5
=+××
⎥
⎦
⎤
⎢
⎣
⎡
=Δ
=
=
7281632128256
2*12*12*12*12*12*02*02*02*1
2*12*12*02*12*122
3457899897969
5949392919
2
0
1
−=++++−=
=++++−=++++
+++++−=∗+∗−=
−−−−
−−−−−
−
=
−
∑
N
i
i
i
N
MSB
bbVa lu e
C
Cdig
digdigT EMPER
CT °==
+
−
=
°
+
=° 8.28
776.2
80
776.2
15272
]/[776.2
][152][
][
][530][25][_][ digdigOTdigRAWTdigTEMPER
−
−=