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PSI System Controls and Diagnostics
12 Circuit overview
+5 V
Digital
inputs
Schmidt
trigger
+1.5 V
Reg
+3.3 V
Reg
+/-15 V
+24V Ext
DC-DC
DC-DC
+24V DC in
+5 VA
Digital
outputs
Line
driver
PCB
temp
sensor
Status
LEDs
Microcontroller
DGnd
TX
Fiber-optic
RX
Analog
inputs
FPGA
ADC
Buffer
Filter
Analog
outputs
DAC
Buffer/gain
Figure 20. M40 block schematic.
All input and output functions are handled through an FPGA. A PIC microcontroller handles
calibration , communications message handling and some ancillary I/O. Incoming 24 VDC
power is fused, clamped against overvoltage and heavily filtered. Isolation DC-DC converters
generate independent voltage rails for the internal analog and digital circuitry.
The eight identical analog inputs, with allowable range -10 to +10V, are inrush limited by 4.7k
resistors and buffered through a unity gain buffer.
M40 User Manual
M40_UM_150226
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