Philips EverFlo Q Service And Technical Reference Manual page 13

4.3.1 POWER
The AC mains power, via the line cord, is brought onto the PCA and the "switched" AC is distributed to the
Compressor, the Cooling Fan and to the AC to DC conversion module. The DC voltages that are generated are
used to power the remaining circuitry.
The PCA contains a 1 Farad "super capacitor" which is used to sound the Audible Indicator when the AC mains
power is absent AND the mains switch is in the ON position. The purpose is to alert the User to the fact that
there has been a loss of AC mains power (that is, an AC mains power failure, a plug removal, a blown fuse). The
circuitry functions as follows:
1. During normal operation, the capacitor is energized (charged) using the +5 VDC. The capacitor
reaches full charge after approximately ½ hour of system on-time.
2. The mains switch has a 2nd set of contacts that are used to determine whether the switch is open
or closed. If the switch is closed (in the ON position) and the microprocessor is not functional (no
DC power), then the backup circuitry is such that it will turn on the Audible Indicator, using the
"super cap" as its energy source.
The "super cap" is capable of sounding the Audible Indicator for a period of greater than 8 minutes, given that it
is fully charged.
4.3.2 MICROPROCESSOR AND ASSOCIATED CIRCUITRY
The remainder of the PCA controller electronics is centered around the MSP430F155 microprocessor. The
microprocessor is the only processing element contained in the EverFlo concentrator. In addition to the
microprocessor, the "remaining circuitry" consists of sensors, LEDS, a piezo Audible Indicator, amplifiers / signal
conditioners, communication buffers and discrete components.
The embedded software, in conjunction with the microprocessor and its associated hardware, is used to control
the sieve valves, measure/monitor the pressure & oxygen levels, control the oxygen sensor, drive the Hour
meter, reports exception conditions to the User via visual and audible indicators and provide diagnostic
information to a Host computer via an RS232 communications interface.
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ECHNICAL NFORMATION
1039055, VER. 06