In-Circuit Digital Functional Testing
QT1100 can functionally test any device working at 5V in in-circuit as well as out-circuit using library defined test patterns.
The Visual WorkStation (VWS) mode allows interactive testing of individual devices, as well as wholeboard test. The Device Under Test (DUT) is tested
under actual in-circuit conditions, that are available on the board. QT1100 uses the back-driving or node-forcing technique to functionally test
devices in-circuit. The back-driving current is limited to 220 mA and back-driving time is limited to 65 m.secs. to comply with the International Defence
Standards 00-53/1.
Auto compensation with Qmax Simulator
While testing devices in-circuit, QT1100 employs the auto-compensation technique. When any of the inputs are shorted together or connected to any power pin,
the input drive pattern or Test Vector is modified on the fly, depending upon the in-circuit links of the device under test. This is essential in order to
avoid the tester driving complementary data to pins shorted together or trying to drive a pattern to a pin connected to the power pin. The expected output
is automatically generated by the Qmax Simulator for the modified input Test Vector. This expected output is compared with the actual output sensed at the
device pin to declare it as good or faulty.
Board Learn & Board Test Modes
The Board Learn mode is used to test the device’s functionality and clip status / link information from a Known Good Board (KGB) and store in a database
file for the future use. A faulty board of identical type can be compared with the learnt board using the Board Test Mode. QT1100 provides the facility
to create a visual board layout on the screen. The comparison results are stored in a log file for future reference.
QSM VI – an advanced tool for failure analysis
QSM VI is an effective tool in detecting failures on custom ICs, passive components on a board, which cannot be functionally tested in the ICFT mode. QSM VI
takes traces by driving a user defined current limited sine wave between any two nodes of the DUT and plotting the voltage vs current trace. For enhanced
fault coverage, QSM VI is capable of taking traces with any of the DUT pins kept as the reference pin.
QSM VI helps detect ESD induced failures.
Auto Guarding
While testing BUS based devices in-circuit, the test result may not be consistent because of the bus contention caused by the other devices connected to the
output bus of the DUT. In such conditions, it will be required to isolate the DUT output pins from other devices coming on the same bus. QT1100 employs the
guarding technique to disable such devices. The auto guarding facility is used to automatically identify the devices, which are causing bus contention to the
DUT, by tracing links between them using the Trace Links option. Information is also displayed about the pins to be guarded and the logic states to guard these
pins.
Logic Analyser
QT1100 wave-form window displays the input drive and the output patterns in a logic analyser style display. Using the Listen mode, user has the option of monitoring
the activity on all the DUT pins simultaneously. Wave patterns upto 8K ticks can be captured and displayed for each pin. The time base per tick is user selectable in
14 steps from 2 µsecs. to 16 milli secs. per tick.
Circuit Tracing
The optional CircuitTracer software is used to learn links between devices on a board. Using two or more clips, links between pins of a device (intra-links) as well as
links between pins of different devices (inter-links) are learnt and stored in a board file. This stored information can be used for future comparison, if a faulty board
is suspected to have a track open / short failure.
The learnt links can be converted into a NetList format which can be used for reverse engineering applications. Using a CAD package, the user can generate schematic
diagram for a board with little or no documentation.
Developing New Device Program
The optional Integrated Device Development Environment (IDDE) software is used to develop new device functional test programs. IDDE has three modes: 1. QDDL uses primitives
to develop programs for SSI and MSI devices; 2. WEST uses program syntax and macros to develop programs for complicated LSI and memory devices; 3. Graphical Test Program
Generator (GTPG), is used to develop library programs for any device by simply drawing the input and output waveforms, without any need for writing complicated syntax.
Short Locator
QT1100 has an in-built Short Locator to detect faulty components causing power line shorts or bus line shorts, which cannot be detected using conventional multi-meters.
Using the 4-wire measurement technique, QT1100 can home-on to the faulty component causing the illegal short. It offers three ranges of measurement at 200 milliOhms, 2 Ohms
and 20 Ohms. The measured resistance value is conveniently displayed as a digital read-out and as a bar graph display.
RCV Measurement & Oscilloscope
The built-in Resistance, Capacitance, Voltage (RCV) Measurement mode is capable of measuing RCV values using Probe and Reference pins. QT1100 is also equipped with two channel
oscilloscope with maximum sampling rate of 500 KHz. The trigger options include auto, normal, single, positive and negative trigger.
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