TPMI Просмотр технического описания (PDF) - PerkinElmer Inc
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TPMI Datasheet PDF : 5 Pages
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TPMI™ - Thermopile Sensor Module With Integrated Signal Processing
Details
The signal voltage generated by the thermopile detector is
preamplified by a programmable low noise amplifier. The
amplification is adjustable in several gain ranges, each
range allowing a 8-bit adjustment in the amplification.
Depending on the object temperature being higher or
lower than the actual ambient temperature of the
thermopile, the thermopile voltage signal can be positive
or negative. In order to allow signal processing of negative
voltages with a single voltage supply system, the internal
amplifiers are referred to an internal bandgap reference of
1.225V.
For offset voltage trimming of the amplification, the
preamplifier is followed by a programmable trimming
stage, generating an offset voltage.
The internal temperature of the thermopile sensor is
recorded by a calibrated temperature sensor with linear
characteristics. The signal of this temperature reference is
amplified and processed by a polynomial processing unit
to adapt it to the non-linear ~T4 shape of the amplified
thermopile curve in order to achieve the optimum of
ambient temperature compensation. The characteristics of
the temperature reference signal (offset and slope) are
adjusted by PerkinElmer during the production process.
The output signal (the object temperature range) can be
adjusted in a wide range to suit the application
requirements. Optionally, via an analog switch, the
temperature compensation can be disabled.
The TPMI additionally features two comparators with
programmable set points and hysteresis, which make an
easy remote temperature control in industrial processes
possible. It can use the TPMI as a temperature dependent
switch for alarm purposes.
Figure 3: Schematics of the TPMI
The ambient temperature compensated signal
representing the object temperature is supplied to the
output VTobj. The temperature reference signal or
alternatively the bandgap reference voltage is available on
a second output pin, VTamb. Both outputs are short circuit
stable.
The control unit offers a bi-directional synchronous serial
interface to access the configuration memory for the
adjustment of ASIC parameters, the trimming of the
ambient temperature sensor, the calibration of the
thermopile detector, and to permanently store information.
After power-on, the stored information is automatically
copied to random access registers that can be changed
via the serial interface. Any changes made to the registers
are lost after power interruption or will be overwritten with
the permanently stored data after the TPMI is powered up
the next time. This gives flexibility to the calibration of the
sensor in the factory and opens up the opportunity to
deliver the customer a plug & play device, which is
possible to be adapted according to the specific
application requirements.
www.perkinelmer.com/optoelectronics
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