2 Theory of Operation
1505-1018-000 08/07
2-23
2.3.6 Power
Management
Board – PMB
The PMB is based on an Atmel Atmega 128 CPU. The PMB performs power selection
between power sources in the following order:
• AC power mains,
• Internal battery.
The PMB regulates the 24 Vdc power supply output down to raw 16 V and 12.5 V power
rails that are used throughout the system (all boards locally regulate from these power
rails).
The PMB controls the charging operation of the internal battery, selecting trickle, bulk,
or float charge status.
The PMB communicates with the DU through the 9.6 Kbaud, RS-232 link (PMB Data I/
O). It sends status commands to the DU concerning the charge status of the internal 24
V battery.
The PMB uses this link as a communication interlock to handle the unit shutdown
sequence. Once a signal is received by the PMB from the mechanical On/Standby
switch, the PMB prompts the DU for a confirmation signal that shutdown is appropriate
(unit is not in a ventilation therapy state). Once the DU relays this confirmation to the
PMB, the power-off sequence is initiated.
The PMB supports the operation of the EC chassis fan and the fan on the PMB
heatsink.
2.3.7 Other
Electronic Items
The EC employs a separate AC to DC switching power supply for providing a nominal
24v voltage level to the PMB. The power supply is capable of regulating 150 W of power
output. A power entry module contains fuses and filters for Mains AC input cables.
Finally, two internal 12v batteries are connected in series to provide an internal backup
24v power source for the system.
For further details, refer to Figure 11-9, "
PMB block diagram
" in Section11.
2 - 12 V
4AHr
Batteries
PMB
Fan
150W Mains
Power Supply
Power Entry
Module
Mains/Bat
Select
Power Management Board
Bat Charge
Cntlr
On/Standby
and
Safety Switch
Power Panel
Connectors
Battery I &
V Monitor
Atmel
ATmega
128 CPU
Fan Cntlrs
16V
Reg
PMB Data I/O
12.5V
Reg
Backup
Audio Power
Chassis Gnd
Vent
Engine
Fan
V Checks
UARTS
PMB
AB.98.
1
9
7
Содержание Engstrom Carestation
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Страница 225: ...ERROR undefined OFFENDING COMMAND STACK ...