Stephan Alia - Page 17

®
3 Components and functions
© F. Stephan GmbH SA-112-0106V1.0-WEM-GB 17
The main task of the sensor board is to convert the analog signals.
Rechargeable battery voltage
"DC_good"
signal
On/off signal
Input voltage
12 V (for heating and valves)
Inspired pressure
Expired pressure
Flow sensor differential pressure
Oxygen sensor cell voltage
Heating
Valves
"Batt_enable"
The power supply for the electronic components is generated by a
DC/DC converter on the sensor board, generating +15V, -5V and -15V.
The input signals for On/Off, DC_good, input voltage and "Batt_enable"
are sent to the SPI bus by a slide register. The input signals for pressure,
flow, O
2
and battery voltage are sent to the SPI bus following
amplification and conversion via an 8-channel AD/12 bit converter.
The AD converter is equipped with protective diodes (max. 5V) on the
input side.
A serial chargeable slide register with power amplifier is used for
triggering the heating and the valves, via the SPI bus.
The respiratory pressure is measured at the inspiration fitting of the
patient part. The pressure present here is conveyed via a tube to the
pressure sensors (respiratory pressure).
For safety reasons, two pressure sensors are provided for measuring the
respiratory pressure.
The differential pressure developing over the resistance body of the PNT
head is used for measurement of the volume flow. This differential
pressure is conveyed via two tubes to the differential pressure sensor.
Main tas
k
Voltage signals (input):
Voltage signals
(output):
Pressure sensors