REV. C

TMP35/TMP36/TMP37

–13–

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.

TMP3x

0.1 F

GND

750

LONG CABLE OR

HEAVY CAPACITIVE

LOADS

Figure 12. Driving Long Cables or Heavy Capacitive Loads

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.