GE b30 Technical Reference Manual

E-PSM(P)W module introduction
1-37
Document no. 2044677-001
Temperature measurement unit
The NTC-resistor value in the probe depends on the patient’s temperature. It is measured with
the following principle described below.
The constant current source is supplied about 38 µA current through the temperature sensor
(YSI 400-series NTC resistor). The constant current is caused a voltage over the temperature
sensor (NTC resistor). The voltage over the temperature sensor is amplified in a differential
amplifier stage. The amplified voltage is transferred to a controller of the STP board through an
A/D converter.
Figure 21 Temperature measurement principle
Invasive blood pressure measurement unit
An isolated +5 V voltage is supplied to the pressure transducer. The differential voltage, which
depends on the pressure and the supplied voltage, is calculated from the bridge connection
(see the formula below).
U
out
= U
in
× pressure × 5 µV, where U
in
is 5 V
⇒ U
out
= 25 µV × pressure [mmHg]
Pressure amplification is realized in the instrumentation amplifier. The gain of the amplifier is
set to keep the level of the signal transferred to the A/D converter within the measurement
range even when there are circumstantial offsets or offsets caused by the transducer. There is
a filter before the amplifier to attenuate high frequency disturbances.
d/dt
0
0
0
0
R
R
R
R
Temperature
sensors T1, T2
constant
current
source
Differential
amplifier
Defibrillation/ESD protection
resistors and diodes
To A/D
converter
0C:7k36
15C:3k54
25C:2k53
38C:1k30
45C: 984
PSM_temp_meas_principle.vsd
Ref2Ref1
T2T1
R R

GE b30 Specifications

General

Model	b30
Manufacturer	GE
Coil Voltage	N/A (Solid State Relay)
Coil Power	N/A (Solid State Relay)
Mechanical Life	N/A (Solid State Relay)
Electrical Life	N/A (Solid State Relay)