Werbung
Verfügbare Sprachen
Verfügbare Sprachen
SaO2 Analog Board - 0670-00-0327
The SaQ2 analog board provides all the patient finger probe excitation and analog sig-
nal processing for measuring SaO2.
The operation of the analog board is controlled by the SaO2 microprocessor, U16 on
the Interface Board, via input buffers (U15, U16, and U30) and latches (U17, U18, and
U19). The signals IRO, IR1, Red 0, Red 1, and Run/Cal determine the operation of the
Digital Sequencer Controller comprised of U23, U24, U25, and U26. The outputs of
U25, S1 through S6, control the pre-amp (U1A) gain and synchronous demodulation
of the detected patient finger probe signal,
The patient finger probe is driven alternatively by Q2 and Q3, which are controlled by
the Digital Sequence Controller outputs IRDRV and REDDRV. G1 provides a clean
power supply voltage for the probe LED emitters.
The probe patient signal enters (J9-13, 14) the board as current pulses in the range of
0.25 to 40 uA. U1B provides filtering for noise above 15KHz. U1A acts as a current to
. voltage converter with gain switchable via U3. U2B is an integrator which maintains
the output of U1B at an average DC voltage of zero. U2A acts as a comparator which
will detect noise voltages larger than +/-6.5V in amplitude. This information is sent to
(J1-32) the SaQ2 microprocessor.
The pre-amp output red and infra-red signal is demodulated by U4, U5, U6, and U7.
The resultant signals are filtered identically (U8, U9) and are alternately selected for fur-
ther amplification via the U19 analog switch.
U11A provides voltage amplification of x1, x2, or xd. Its output is amplified by U11B,
which uses the microprocessor controlled DAC (U20, U21) valtage ta maintain the
resultant signal.in the amplifier linear region. U11B provides switchable gains of x5,
x22, and x100. Its output is sampled by U13 for amplitude digitization via comparator
U14, using the DAC voltage for comparison.
The signal is sent to the interface Board
(J1-30).
'
Regulated power for the analog board is provided by U27 and U28. Reference vol-
tages of -8V and +3.35V are generated by U29 and U22.
1-55
Werbung
