Texas Instruments 2.7V, 15.6mV deg C, SOT-23 Temperature Sensor LM62EVAL LM62EVAL Datenbogen
Produktcode
LM62EVAL
SNIS105E – JUNE 1999 – REVISED MARCH 2013
CIRCUIT BOARD
½
″
Square Printed Circuit Board with 2 oz. Copper Foil or Similar.
Figure 12. Printed Circuit Board Used for Heat Sink to Generate All Curves
Mounting
The LM62 can be applied easily in the same way as other integrated-circuit temperature sensors. It can be glued
or cemented to a surface. The temperature that the LM62 is sensing will be within about +0.2°C of the surface
temperature that LM62's leads are attached to.
or cemented to a surface. The temperature that the LM62 is sensing will be within about +0.2°C of the surface
temperature that LM62's leads are attached to.
This presumes that the ambient air temperature is almost the same as the surface temperature; if the air
temperature were much higher or lower than the surface temperature, the actual temperature measured would
be at an intermediate temperature between the surface temperature and the air temperature.
temperature were much higher or lower than the surface temperature, the actual temperature measured would
be at an intermediate temperature between the surface temperature and the air temperature.
To ensure good thermal conductivity the backside of the LM62 die is directly attached to the GND pin. The lands
and traces to the LM62 will, of course, be part of the printed circuit board, which is the object whose temperature
is being measured. These printed circuit board lands and traces will not cause the LM62's temperature to deviate
from the desired temperature.
and traces to the LM62 will, of course, be part of the printed circuit board, which is the object whose temperature
is being measured. These printed circuit board lands and traces will not cause the LM62's temperature to deviate
from the desired temperature.
Alternatively, the LM62 can be mounted inside a sealed-end metal tube, and can then be dipped into a bath or
screwed into a threaded hole in a tank. As with any IC, the LM62 and accompanying wiring and circuits must be
kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may operate at cold
temperatures where condensation can occur. Printed-circuit coatings and varnishes such as Humiseal and epoxy
paints or dips are often used to ensure that moisture cannot corrode the LM62 or its connections.
screwed into a threaded hole in a tank. As with any IC, the LM62 and accompanying wiring and circuits must be
kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may operate at cold
temperatures where condensation can occur. Printed-circuit coatings and varnishes such as Humiseal and epoxy
paints or dips are often used to ensure that moisture cannot corrode the LM62 or its connections.
The thermal resistance junction to ambient (
θ
JA
) is the parameter used to calculate the rise of a device junction
temperature due to its power dissipation. For the LM62 the equation used to calculate the rise in the die
temperature is as follows:
temperature is as follows:
T
J
= T
A
+
θ
JA
[(+V
S
I
Q
) + (+V
S
−
V
O
) I
L
]
(1)
where I
Q
is the quiescent current and I
L
is the load current on the output. Since the LM62's junction temperature
is the actual temperature being measured care should be taken to minimize the load current that the LM62 is
required to drive.
required to drive.
The table shown in
summarizes the rise in die temperature of the LM62 without any loading, and the
thermal resistance for different conditions.
Table 1. Temperature Rise of LM62 Due to Self-Heating and Thermal Resistance (
θ
JA
)
SOT-23
SOT-23
no heat sink
(1)
small heat fin
(2)
θ
JA
T
J
−
T
A
θ
JA
T
J
−
T
A
(°C/W)
(°C)
(°C/W)
(°C)
Still air
450
0.17
260
0.1
Moving air
180
0.07
(1)
Part soldered to 30 gauge wire.
(2)
Heat sink used is ½
″
square printed circuit board with 2 oz. foil with part attached as shown in
.
6
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