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ManualsBrandsMidmark ManualsGadgetsIQmark Digital ECG PDA
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IQmark Digital ECG Operation Manual
51
Isolated Serial Interfaces
To provide the maximum safety for the patient, the IQmark Digital ECG hardware and
the PC are isolated with an optical coupler and/or isolated DC to DC converters. The
serial signal sent out by the PIC microcontroller is coupled optically to the PC system
either through the RS232 or USB interface. There is no electrical connection between
the patient and the PC system. The isolation circuit can withstand up to 1000Volts.
Lead-Off Detector
The IQmark Digital ECG has a built in lead off detection circuit. The lead-off circuit
senses the lead off condition and reports to the PIC microcontroller. The PIC
microcontroller sends out the lead off condition to the PC through the serial interface.
Pacemaker Detector
The pacemaker detection circuit in the IQmark Digital ECG ensures the device’s
capability of printing the ECG signal in the presence of pacemaker pulses with
amplitudes between 2 and 250 mV, duration between 0.1 and 2.0 ms recommended by
AAMI EC-11.
DC-DC Power Converter
The IQmark Digital ECG (42 Series / RS232) uses two AA batteries to supply its power.
The IQmark Digital ECG (43 Series / USB) does not require the use of batteries. The USB
port of the host computer provides the operating power. A step up DC-DC converter is
used to provide a 4.5Volt power source. Two 3.3Volt regulators are used to provide two
3.3Volts power source for the analog circuits and digital circuit for the unit. There is also
a negative voltage converter used to generate a 3.3Volt power source for the analog
circuit. A Linear Technology 1.25Volt micropower shunt reference regulator provides
precision 1.25Volt reference voltage.
The IQmark Digital ECG (42 Series / RS232) power is switched on or off via the switch
marked I/O on the top label. The IQmark Digital ECG (43 Series / USB) power is switched
on or off by the ECG program through the USB port. Isolation is provided for signals
entering the ECG module and can withstand up to 1000Volts.
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