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Chapter 3
Theory of Operation
1062788
BiPAP Vision Service Manual © Respironics, Inc.
3-11
3.2.4
Watchdog and Power On Reset Circuit
The microcontroller generates pulses that toggle the watchdog timer circuit
when the system is running. If watchdog circuit is not toggled within a 70-ms
period, the microcontroller resets. The microcontroller monitors watchdog
status, and clears the reset when it receives a watchdog timer reset signal. The
system does not shut down in case of a watchdog timeout.
The power on reset circuit monitors the logic supply voltage through a voltage
divider circuit. A separate 1.3-V threshold detector for this power fail warning.
If a low supply voltage level is detected, the microcontroller resets.
3.2.5
Error Line Control Circuit (ELC)
The ELC includes ELC #1, ELC #2, and a 2.38-V reference monitor.
•
ELC #1 is designed to allow normal operation only when the PC and
DC boards are connected. Removing either board or a microcontroller
error signal cause an ELC fault condition.
•
ELC #2 includes pulse generators and pulse detectors on the PC and
DC boards, and an ELC fault condition occurs if a minimum number of
missing pulses occur.
•
The 2.38-V reference monitor includes a window comparator that
monitors the reference signal and alerts the microcontroller if the
signal is out of tolerance.
3.2.6
Microcontroller Interface
The microcontroller interface includes:
•
Microcontroller: the MC board uses a microcontroller with a crystal
oscillator. A phase-locked loop in the microcontroller generates an
internal clock signal that helps to reduce EMI interference. The
microcontroller includes 7 interrupt lines and 7 chip select lines.
•
Memory: a memory decoder PAL decodes the microcontroller chip
selects. Program code is stored in EPROM and data is stored in
nonvolatile, static RAM.
•
ICB interface: a PAL provides the logic that controls the ICB interface
•
Serial interface: +5 V logic voltage is converted into +10-V RS-232
voltages through transmit (TXD) and receive (RXD) lines.
Содержание BiPAP Vision
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Страница 212: ...Appendix A A 42 BiPAP Vision Service Manual Respironics Inc 1062788 This page is intentionally blank ...
Страница 221: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 3 Figure C 2 MC Board Analog Outputs ...
Страница 222: ...Appendix C C 4 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 3 MC Board Watchdog Real Time Clock ...
Страница 224: ...Appendix C C 6 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 5 MC Board Power Supply Status ...
Страница 225: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 7 Figure C 6 MC Board Bypass Circuitry ...
Страница 227: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 9 Figure C 8 DC Battery and Indicator Circuitry ...
Страница 228: ...Appendix C C 10 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 9 DC ELC Circuitry ...
Страница 231: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 13 Figure C 12 DC Microcontroller Interface ...
Страница 232: ...Appendix C C 14 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 13 DC Board Power Conversion Circuitry ...
Страница 234: ...Appendix C C 16 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 15 DC Board ELC Circuitry ...
Страница 236: ...Appendix C C 18 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 17 DC Board Microcontroller Interface ...
Страница 237: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 19 Figure C 18 Pressure Control PC Board CPU ...
Страница 238: ...Appendix C C 20 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 19 PC Board Motor Controller ...
Страница 239: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 21 Figure C 20 PC Board Pressure Sensors ...
Страница 240: ...Appendix C C 22 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 21 PC Board Valve Drivers ELC ...
Страница 241: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 23 Figure C 22 PC Board Bypass Pullup ICB Databus ...
Страница 242: ...Appendix C C 24 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 23 Air Flow Module AFM ...
Страница 243: ...Appendix C 1062788 BiPAP Vision Service Manual Respironics Inc C 25 Figure C 24 Oxygen Module OM ...
Страница 244: ...Appendix C C 26 BiPAP Vision Service Manual Respironics Inc 1062788 Figure C 25 Power Supply Subsystem PSS ...