ZOLL Base Powercharger 4x4, Руководство по обслуживанию

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FUNCTIONAL DESCRIPTION
IV-9
Test Switch Interface Circuitry
A simple interface circuit and a single input port line is used to monitor the test switch
located on the LED PCB. An internal pull-up resistor in the microprocessor holds the
input pin high (port P1.6) until the test switch is pressed causing this signal to short to
ground.
R134 limits the current into the microprocessor from a possible short circuit and D106
is used as a guard against static discharge.
Battery Voltage Sense Circuitry
The microprocessor monitors the switchmode power supply output and the battery
voltage over a range of 8.5 to 16.5 volts to determine the battery's charge status and if
it or the internal control electronics or the power supply has failed. The
microprocessor resolves the voltage reading to within 50 millivolts (33mV, 8 bit) in
order to support the battery charging algorithm requirements.
Op amp U105A forms a basic amplifier circuit with a gain of approximately -0.574 and
an offset of 8.01V (established by the resistor combination R111, R112 and R110).
Resistors R133 and R132 form a voltage divider to drop the battery voltage by a factor
of 6 to keep the signal range within the input requirements of the op amp device
(U105A). The resulting output signal (at U105.1), ranging from 0 to 4.85 volts is read
by the microprocessor at its analog input (U104.13).
Capacitors C111 and C108 provide noise filtering while and capacitors C109 and
C110 provide RF interference and static discharge protection. C119 is a power supply
bypass capacitor.
A/D (voltage)=5-((Battery voltage-8.01)*0.574)
Current Sense Circuitry
The microprocessor monitors the supply current over a range of approximately 0 to 2
amps to determine the battery's charge status or if a control circuit has failed. The
microprocessor resolves a current reading to within 8.3 milliamps in order to support
the battery charging control requirements.
OP amp U102B forms a basic amplifier circuit with a gain of approximately 24 to
amplify the current sense signal through the 100 milliohm resistor (R127). The gain of
the circuit is established by resistor values R125 and R126. The resulting output
signal (I_SENSE at U102.7), ranging from 0 to 4.85 volts is read by the
microprocessor at its analog input (U104.16).
Capacitor C120 provides noise filtering while and capacitors C114, C115, and C116
provide RF interference and static discharge protection. R 106 is a balancing resistor
in the non-inverting input line to the amplifier.
A/D (Current)=Battery Current*2.37