Revision B MAC™ 5000 resting ECG analysis system 2-9
2024917-010
Equipment Overview: Theory of Operation
Power Supplies
The MAC 5000 requires several regulated voltages for operation of its
various components. The Main Regulator provides most of the supply
rails. The supply rails are:
+3V-C
MAC 5000 is never truly “off”. The system supervisor microcontroller
(MOE) must constantly monitor the power key and perform battery
charging/gauging. The clock/calendar in the Super I/O chip must also
maintain time/date when the machine is off. These functions are powered
from the +3V-C rail, which provides power continuously from the battery
pack regardless of the state of the rest of the system. The Main Regulator
produces +3V-C directly from the battery rail via an internal low current
linear regulator. Only 5mA are available from +3V-C, so it must be used
sparingly.
NOTE
The MAX782’s low current regulator is dreadfully inefficient.
Regulator Q current appears to be about 3x the load current. This
makes conservation of load on +3V-C crucial.
+3V-M
Most of the MAC 5000 hardware runs from +3V-M. The MAX782
provides this rail from the battery via a PWM synchronous switching
regulator. Moe controls +3V-M in tandem with +5V-M.
+3V-EMI
This is simply an RF blocked feed from +3V-M. +3V-M load is contained
within the CPU board. Power for devices for external functions is
supplied by +3V-EMI. The isolation of +3V-EMI from +3V-M may be
unnecessary as the concept has never been tested for its effect.
+5V-M
The MAC 5000 is not fully in the 3V age. The Super I/O, floppy diskette
drive and thermal printhead all require 5V power. The MAX782 provides
this rail via another PWM synchronous switching regulator. Moe
controls +5V-M in tandem with +3V-M.
+5V-EMI
Similar to +3V-EMI, this rail is an RF blocked feed from +5V-M, used to
power devices for external functions. The isolation of +5V-EMI from
+5V-M may be unnecessary as the concept has never been tested for its
effect.
To Next Page
Loading...
Need help?
General
