A complete LVTGO-VBS system consists of the LVTGO-VBS hardware and the EMC test software, itself consisting of the LVTest GUI running on a host PC.
The LVTGO-VBS LVTest GUI allows you to configure and perform many test types, including the testing of starting or cranking profiles, the introduction of short voltage interruptions, the slow increase or decrease of operating voltage and more.
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Using the LVTest GUI
1. Select your waveform
Select the generic type of waveform you want to deliver. These are based on a range of vehicle phenomena. Alternatively select from a range of pre-configured profiles based upon common automotive standards.
2. Configure parameters
Use simple text fields to submit values for time and voltage for each waveform parameter and how you’d like these to randomise. This includes the distribution of random values and the maximum and minimum possible values.
3. Deliver the waveform
Play the waveform to the device under test via the GUI or automated triggering, logging results where necessary. If you wish to deliver an entirely custom waveform this can be specified via a CSV file.
Cranking waveform split into segments of time and voltage
All LVTGO-VBS units allow engineers to generate waveforms associated with cranking, poor connections and other common phenomena. In real vehicles, these waveforms appear to be random, but they can be characterised through segmentation varying by factors including time, voltage and slew rate. Using this technique, engineers can re-create close to real-world conditions within the laboratory. What’s more, these tests are fully repeatable.
This pseudo-randomisation allows engineers to achieve a greater level of test coverage, performing thousands of cycles close to known failure points. Once issues occur, the cycle responsible can be quickly identified and repeated, whether the overall test took minutes, hours or days. Ultimately, this frees up time for more complicated and valuable work.
All electronic control units within vehicles are connected to ground via the body. As time progresses, these connections degrade for a host of reasons including repeated movement, accidental damage and chemical spillage. This changes the ground reference of the system, often by margins that could make an on signal appear like an off signal. All products in the LVTGO-VBS range are able to perform ground offset testing to simulate the above degradation. Furthermore, they are able to conduct ground offset and voltage profile testing at the same time, increasing overall levels of test coverage.
Key waveform types delivered by the LVTest GUI
The LVTGO-VBS can subject the device under test to various waveform types commonly seen within vehicles, including the following:
Random, parameterised, repeatable voltage profiles
Engine starting or cranking waveforms create large drops in voltage upon the ignition sequence of vehicle engines. These drops recover as the alternator starts to charge the battery. The LVTGO-VBS unit is able to generate parameterised voltage profiles simulating these waveforms, allowing engineers to deliver broad test coverage yet be able to narrow in on areas of concern, as they appear. For example, since variations in voltages between the thresholds of two CPUs in a system are known to cause issues during low voltage testing, randomised testing might be configured between these two values.
Voltage profiles that lower or raise over custom periods of time
Ramp waveforms allow engineers to test how a system or sub-system might react after being left unattended for custom periods of time. The LVTGO-VBS range is able to simulate voltage ramps from a few milliseconds, typically from seconds to a number of days, in order that the system’s performance under quiescent current draw conditions can be analysed. The key scenario under test here is that of a vehicle left unattended over a few weeks or so. During this time, components may be exposed to a voltage that causes the system to freeze, or can leave permanent damage.
Fast Transient Burst Noise
Periodic interference attributable to a poor connection
Fast Transient Burst Noise is caused when cables, plugs or bare wires cause intermittent or short circuits, disrupting the power supply. This interference is likely to cause a vast array of potential failures, due to the large number of voltage changes it can bring about, and the high frequency of those voltage changes. The LVTGO-VBS range is able to simulate waveforms that are commonly generated by this kind of interference, allowing engineers to assess equipment under test for failures caused by these significant and frequent voltage profile fluctuations.
Fast voltage pulses of down to three microseconds
Some transient tests require very short-term disruptions with fast edges. We are able to provide a specific unit that also accommodates this type of testing, utilising modified driver hardware and software to achieve output switching down to three microseconds. The output may be configured to produce a stream of rising or falling pulses between two nominated voltage levels. This level of performance lies far in excess of any specialised power supply unit, both actively sourcing from and sinking to the power source at a vastly increased rate.
Constant slope ramps
Voltage profiles rising or falling between values
Ramping voltage waveforms of this nature are utilised by engineers to test to the CI265 standard, and a range of other voltage dependent threshold issues. Like other types of ramp test, these waveforms is used to assess the likelihood or particular voltages generating failures within a component under test, or causing damage to that component under test. It involves the ramping of a voltage profile to a succession of user configured values, again incorporating randomisation to achieve the greatest possible levels of test coverage.
Voltage profiles produced according to requirements
The LVTGO-VBS range is capable of replicating voltage waveforms captured via spreadsheet data, in CSV format. In combination with the supplied GUI, engineers can feed required settings into the unit, for playback to devices under test. If you have waveform data that you are attempting to reproduce, for example that captured from an oscilloscope or generated as the result of a formula, importing this information is a quick and simple process. The time taken to configure and run such tests is vastly reduced.
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