Pressure Module, M-P and Pressure Temp Module, M-PT
Document No. 800 1013-1
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The reset line is an open collector type with a pull-up resistor so that the microprocessor is able to
use its internal watchdog function.
Power supply section
Isolated supply voltage of the module is developed from +15 Vdirty voltage from the Central Unit.
Power supply is a switched-mode circuit, where FET transistor switch is controlled by an oscillator
using bipolar timer. The frequency of the oscillator is about 30 kHz and pulse ratio 50 %.
Controlling of the FET switch is slowed to suppress spurious interference.
A special pulse transformer is used in the circuit. The transformer secondary circuit uses normal
linear regulators except for +5 V which uses a low drop type linear regulator.