MAGNET POWER SUPPLY SYSTEM 7000
27
DANFYSIK A/S - DK 4040 JYLLINGE - DENMARK.
4.2
Display controller module.
Schematic:
85089-1 & 2
Assy.:
85088
The display controller module contains the display, local buttons, DAC for the set value, ADC
for the read back, serial interface and the controlling micro-processor.
4.2.1
Micro-Processor
The micro-processor circuit is the intelligent part of the system and build around a Zilog micro-
processor U8,
The CPU runs at 20MHz, controlled from the crystal Y1.
The micro-processor has built-in "Watchdog" circuit and will reset the CPU, if it for some
reason stops to refreshing the watchdog.
As memory it uses its internal FLASH EEPROM for the PGM storage and U20 as the data
storage “FRAM type FM25CL64-S with 64Kbit capacity” as well as its internal RAM.
4.2.2
Display
The display consists of 12 single LEDs for status and 2x6 common anode 7-segments LEDs for
displaying set/output currents and voltage respectively. The display refreshment is done
through multiplexing controlled by the CPU.
For driving the segments, buffer U9 and U18 with transistor Q1 and Q2 are used.
Connecting the power supply as slave in a master slave configuration (in parallel with another
supply) the 7 segment display of the slaves will be turned off. The master will automatically
display the total current of all paralleled units.
4.2.3
DAC circuit
The DAC circuit converts the serial digital set value to a voltage reference.
The circuit is built around U1 for the I-reference set value and U10 for the V-reference set
value.
The DAC circuit delivers a bipolar output voltage proportional with the digital input value.
