TMP35/TMP36/TMP37
Driving Long Cables or Heavy Capacitive Loads
Although the TMP3x family of temperature sensors is capable
of driving capacitive loads up to 10,000 pF without oscillation,
output voltage transient response times can be improved with
the use of a small resistor in series with the output of the temperature
sensor, as shown in Figure 12. As an added benefit, this resistor
forms a low-pass filter with the cable’s capacitance, which helps
to reduce bandwidth noise. Since the temperature sensor is
likely to be used in environments where the ambient noise level
can be very high, this resistor helps to prevent rectification by the
devices of the high frequency noise. The combination of this
resistor and the supply bypass capacitor offers the best protection.
+VS
Commentary on Long-Term Stability
The concept of long-term stability has been used for many years
to describe by what amount an IC’s parameter would shift dur-
ing its lifetime. This is a concept that has been typically applied
to both voltage references and monolithic temperature sensors.
Unfortunately, integrated circuits cannot be evaluated at room
temperature (25°C) for 10 years or so to determine this shift. As
a result, manufacturers very typically perform accelerated life-
time testing of integrated circuits by operating ICs at elevated
temperatures (between 125°C and 150°C) over a shorter period
of time (typically, between 500 and 1000 hours).
As a result of this operation, the lifetime of an integrated circuit
is significantly accelerated due to the increase in rates of reac-
tion within the semiconductor material.
0.1F
TMP3x VOUT 750⍀
LONG CABLE OR
HEAVY CAPACITIVE
LOADS
GND
Figure 12. Driving Long Cables or Heavy Capacitive Loads
REV. C
–13–