Newport 8000 - TEC Module Theory of Operation; TEC Interface; Limit DAC; Figure 29 - TEC Board Module Diagram

64 Chapter 4 Temperature Controller Module Operation
4.6 TEC Module Theory of Operation
Figure 29 shows the functionality of the TEC module. The following sections detail
the theory of operation for each of the blocks in Figure 29.
O
ptically
Isolated
Serial Bus
Bipolar
Output
Stage
Limit DAC
P
roportional Amp
Integral Amp
Differential
Sensor
Select and
TEC
Sensor Lines
A/D
Converter
Limit Set Point
PI Loop
Set
Set Point
DAC
Actual
Heat/Cool Lines
Current
Amps
Amp
To Microprocessor
Figure 29 - TEC Board Module Diagram
4.6.1 TEC Interface
The TEC interface provides optically isolated serial communications between the
TEC board and the microprocessor. Control signals are passed to the TEC board to
set the TEC board status, current limit, and temperature set points. Instructions and
data are sent over the serial interface to the optical barrier. Status and data are
serially passed back to the microprocessor.
4.6.2 Limit DAC
The microprocessor loads the digitally stored current limit value into the current limit
12-bit DAC. The Limit DAC converts the digital limit signal from the
microprocessor to a voltage which becomes the limit voltage for the Bipolar Output
Stage. The current limit value is updated at power-up, at a "bin" recall, and whenever
the LIM ITE value is changed.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com