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System Control
System Control
System Control
System Control
LP6 Plus, LP10, and LP20 Technical Manual
November 2000
Page 4-11
Page 4-11
Page 4-11
Page 4-11
adjusted as necessary for the patient compliance/resistance. The
controller limits motor drive power to an amount that will not pro-
duce excessive patient pressures or damage to the drive electronics.
Anytime the microprocessor fails to complete its program cycle,
motor movement stops, all front-panel LEDs light, and a continuous
alarm sounds. During internal battery-powered operation, if the
system voltage drops too low, the ventilator is turned off and the
remainder of the internal battery power is used for an alarm.
The RAM (U1 used on older through-hole board or U23 on the newer
surface-mount board) contains 2 kB of memory. About 800 bytes
are used for temporary storage. The remainder is used to store pres-
sure and position data during piston stroke. It is from here that the
data are obtained for printout.
EEPROM (U24 used on older through-hole board or U26 on the
newer surface-mount board) retains memory without power, so it
stores data such as calibration, machine hours, etc. The Time-of-
Day Chip (U10 used on older through-hole board or U17 on the
newer surface-mount board) uses its own battery to maintain the
date/time function while power is off.
Analog to Digital Converter
Analog to Digital Converter
Analog to Digital Converter
Analog to Digital Converter
An eight-channel analog-to-digital converter (U19 used on older
through-hole board or U15 on the newer surface-mount board) con-
verts the following signals:
•
Patient Pressure, for meter display, low and high pressure alarm
sensing and printout
•
Amplified Patient Pressure, for patient effort triggering
•
Volume Control Setting
•
Patient Effort Control Setting
•
Internal Battery Voltage
•
Internal Battery Current
•
External Battery Voltage
•
External Battery Current
Digital to Analog Converter
Digital to Analog Converter
Digital to Analog Converter
Digital to Analog Converter
A D/A converter is required to convert data to an analog format.
Components U16 and U17 on older through-hole board, or U16 and
U21 on the newer surface-mount board, serve this function. U17 or
U21 converts a digital value to make it applicable for motor speed
control. U16 supplies the front panel meter. The data from the pres-
sure transducer is converted to a digital value for use by the micro-
processor and must be reconverted as an input to the meter.