Teledyne ADFM Analog Output Module, Техническое руководство, Страница: 70 / 156

Appendix A
A-3.4 Temperature Interface
The transducer’s ambient temperature is sensed by an accurately linearized
termistor (T_SENSE). The termistor’s temperature dependent output volt-
age is connected to an amplifier (S_AMP), where it is scaled, and buffered.
The transducer then digitizes the scaled buffered output voltage. The result
is available for the ADFM’s Electronics Unit via the serial interface port.
Since the temperature signal (TEMP) is ratiometric to the temperature sen-
sor’s supply voltage, the transducer controller also digitizes the sensor’s
supply voltage.
A-3.5 Transducer Power Supply
The transducer power supply terminals are labeled VXDR. The supply
voltage is lowpass filtered and regulated by a low-dropout linear voltage
regulator (PWR-REG). The 5.0-volt output VAA1 of the regulator is the
primary supply for all transducer modules. A 2.50-volt reference voltage
VREF provides all bias voltages needed for the pre-amplifier and the buffer
stage. For build-in self-test purposes, it is also provided to the transducer
controller’s A/D-converter. To save energy, the temperature sense circuitry
and its scaling amplifier are power strobed, that is, power is only provided
when a temperature measurement is needed. A solid state switch (T-EN)
connects VAA1 to the power supply of the temperature circuitry under the
controller’s command.
page A-6 MGD Technologies, Inc.