© Midmark Corporation 2016
and built-in serial interfaces for the A/D converter and RS232 devices. The microcontroller receives the digitized ECG data from the AD
converter, and then encodes the data with packets and sends out to the PC through serial interface circuitry. The setting for the RS232
is 8 bit data, 1 bit stop, no parity, and 115,000- baud rate, and is usually handled automatically. The settings for USB are automatic and
are not user selectable.
Isolated Serial Interfaces
To provide the maximum safety for the patient, the IQecg
®
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 IQecg
®
has a built-in lead off detection circuit. The lead-off circuit senses the lead-off condition and reports it 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 IQecg
®
ensures the device’s capability of printing the ECG signal in the presence of pacemaker
pulses with amplitudes between 2 and 250 mV, with a duration between 0.1 and
2.0 ms, as recommended by AAMI EC-11.
DC-DC Power Converter
The USB model of the IQecg
®
devices does not require the use of batteries. The USB port of the host computer provides the
operating power. A step-up DC-to-DC converter is used to provide a 4.5Volt power source. Two 3.3Volt regulators are used to
provide two 3.3Volts power sources for the analog circuits and digital circuit for the unit. There is also a negative voltage converter,
which is 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.
Isolation is provided for signals entering the ECG module, and can withstand up to 1000Volts.
System Maintenance and Obtaining Service
The IQecg
®
is a portable device and requires little maintenance. To ensure the best performance of the device, the following
procedures are recommended:
• Keep the patient cable clean.
• Do not unplug the patient cable from the IQecg
®
hardware.
• When the device LED turns red or the computer screen displays a low battery message, (45 Series
/ RS232 version only), replace the batteries inside the unit before continuing.
The IQmark and IQecg Digital ECG acquisition modules contain no user adjustable or serviceable parts, and are designed to operate
without adjustment for the lifetime of the product.
However, electronic equipment can be subject to wear and damage that can cause malfunctions. A certification policy is the
responsibility of the end user, and is subject to the end user’s business practices, which may require it. Certification provides peace of
mind that the device continues to work within factory specifications. Certifications can be purchased directly from Midmark.
Please contact Technical Service at (800) 624-8950 or (844) 856-1230, option 2, with questions or to make arrangements for the
certification of an IQmark
®
Digital ECG or IQecg
®
Digital ECG device.
Return authorization is required prior to the return of the
device. Midmark Technical Service will issue a Return Materials
Authorization (RMA) number prior to shipment.
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