Accutorr Plus Service Manual - Mindray

Figure 2-12
2.2.12 Masimo Interface Board Theory of Operation
Introduction
The Accutorr Plus Masimo interface board (P/N: 0670-00-0716) provides an isolated
data and power interface between the Accutorr Plus and the Masimo MP-3 Pulse
Oximetry Module.
The patient isolation requirement for the Masimo section is 1500VAC, less than or equal
to 1mA leakage current, from input connectors J1 and J4-all terminals to J2-all terminals.
The isolated DC/DC converter, T1, supplies the regulated+5DIG as required by the
Masimo MS-3 Pulse Oximetry Module. The digital 5V is then utilized to generate the
analog 15V used by the MS-3. The optocouplers (U1 and U2) isolate the signals used
for bidirectional serial communication with the Masimo MS-3 Pulse Oximetry Module.
Control signal, SpO2_COMM at J4 will allow the Accutorr Plus software to interrupt
the serial transmission for future options. Future interface to the Display Controller
board (at J3) will provide isolated 9volts to the Front End
Theory of Operation
An overall block diagram of the interface board is shown in Figure 1 below. All data and
control lines interfaced to the SpO2 Module are opto isolated. Power to the SpO2
Module is isolated by a DC/DC converter with the input coming directly from the
CPU/LED Module.
2-32 Revised 12/20/00
Accutorr Plus Service Manual
Chapter 2 - Theory of Operation