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
) or with an extended SPC frame (see
). 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
and reading
the TEMPER bits. TEMPER is a signed register, to convert the value to digits proceed as described in
. As an example, for a TEMPER value of 110111000
B
, the value in digits is calculated in
(4.4)
Therefore, the temperature in degrees Celsius is calculated in
(4.5)
TEMPER typical accuracy error is /-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
:
(4.6)
)
(
∑
×
+
×
×
=
×
=
Δ
Δ
+
=
+
=
Q
Q
Q
DD
DD
thJA
TOT
thJA
A
J
thCA
thJC
thJA
I
V
I
V
R
P
R
T
T
T
T
R
R
R
(I
DD
, I
Q
> 0, if direction is into IC)
[ ]
[ ] [ ]
(
)
K
VA
A
V
W
K
T
mA
I
V
V
DD
DD
5
.
10
0
014
.
0
5
150
14
5
=
+
×
×
⎥⎦
⎤
⎢⎣
⎡
=
Δ
=
=
72
8
16
32
128
256
2
*
1
2
*
1
2
*
1
2
*
1
2
*
1
2
*
0
2
*
0
2
*
0
2
*
1
2
*
1
2
*
1
2
*
0
2
*
1
2
*
1
2
2
3
4
5
7
8
9
9
8
9
7
9
6
9
5
9
4
9
3
9
2
9
1
9
2
0
1
−
=
+
+
+
+
−
=
=
+
+
+
+
−
=
+
+
+
+
+
+
+
+
+
−
=
∗
+
∗
−
=
−
−
−
−
−
−
−
−
−
−
=
−
∑
N
i
i
i
N
MSB
b
b
Value
C
C
dig
dig
dig
TEMPER
C
T
°
=
=
+
−
=
°
+
=
°
8
.
28
776
.
2
80
776
.
2
152
72
]
/
[
776
.
2
]
[
152
]
[
]
[
]
[
530
]
[
25
]
[
_
]
[
dig
dig
O
T
dig
RAW
T
dig
TEMPER
−
−
=