LM26CIM5-TPA National Semiconductor, LM26CIM5-TPA Datasheet - Page 6

• Manufacturer Part Number: LM26CIM5-TPA
• Description: IC, LOW POWER THERMOSTAT, ± 3°C, SOT23-5
• Manufacturer: National Semiconductor

Specifications of LM26CIM5-TPA

• Ic Output Type: Digital
• Sensing Accuracy Range: ± 3°C
• Supply Current: 16µA
• Supply Voltage Range: 2.7V To 5.5V
• Sensor Case Style: SOT-23
• No. Of Pins: 5
• Termination Type: SMD
• Filter Terminals: SMD
• Rohs Compliant: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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TABLE 1. Resistive compensation for capacitive loading
NOISE CONSIDERATIONS
The LM26 has excellent power supply noise rejection. Listed
below is a variety of signals used to test the LM26 power sup-
ply rejection. False triggering of the output was not observed
when these signals where coupled into the V+ pin of the
LM26.
•
•
•
Testing was done while maintaining the temperature of the
LM26 one degree centigrade way from the trip point with the
output not activated.
MOUNTING CONSIDERATIONS
The LM26 can be applied easily in the same way as other
integrated-circuit temperature sensors. It can be glued or ce-
FIGURE 2. Resistor placement for capacitive loading
square wave 400kHz, 1Vp-p
square wave 2kHz, 200mVp-p
sine wave 100Hz to 1MHz, 200mVp-p
≤
100nF
b) R in series with signal path
C
≥
10nF
100pF
a) R in series with capacitor
1nF
LOAD
1µF
compensation of V
of V
TEMP
TEMP
R (Ω)
8200
3000
1000
430
10132317
0
10132318
6
mented to a surface. The temperature that the LM26 is sens-
ing will be within about +0.06°C of the surface temperature to
which the LM26'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 temper-
ature between the surface temperature and the air tempera-
ture.
To ensure good thermal conductivity, the backside of the
LM26 die is directly attached to the GND pin (pin 2). The tem-
peratures of the lands and traces to the other leads of the
LM26 will also affect the temperature that is being sensed.
Alternatively, the LM26 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 LM26 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 conden-
sation 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 LM26 or its connections.
The junction to ambient thermal resistance (θ
rameter used to calculate the rise of a part's junction temper-
ature due to its power dissipation. For the LM26 the equation
used to calculate the rise in the die junction temperature is as
follows:
where T
voltage, I
on the V
and I
LM26's junction temperature is the actual temperature being
measured, care should be taken to minimize the load current
that the LM26 is required to drive.
The tables shown in
tance for different conditions and the rise in die temperature
of the LM26 without any loading on V
resistor on an open-drain digital output with a 5.5V power
supply.
FIGURE 3. Thermal resistance (θ
Still Air
Moving Air
DO
A
TEMP
is the load current on the digital output. Since the
Q
is the ambient temperature, V
is the quiescent current, I
output, V
due to self heating (T
(°C/W)
TBD
250
no heat sink
θ
JA
Figure 3
SOT23-5
DO
is the voltage on the digital output,
T
TBD
0.11
(°C)
J
summarize the thermal resis-
−T
A
JA
L_TEMP
) and temperature rise
TEMP
J
+
(°C/W)
−T
small heat sink
TBD
TBD
is the power supply
θ
A
JA
is the load current
and a 10k pull-up
)
SOT23-5
JA
) is the pa-
T
TBD
TBD
(°C)
J
−T
A
(3)