Troubleshooting Your Design with the TDS2000C Series Oscilloscopes
Table of Contents Troubleshooting Your Design with the TDS2000C Series Oscilloscope..................... 4 Getting Started........................................................................................................ 5 Capture Elusive Glitches and Anomalies............................................................... 6-7 Debug Digital Timing Problems................................................................................ 8 Verify Timing Relationships......................................
Troubleshooting Your Design with the TDS2000C Series Oscilloscope Today’s engineers and technicians face increasingly complex and critical troubleshooting tasks. New digital designs often challenge designers with new problems to find: race conditions, transients, signal aberrations, bus contention problems, etc. And, of course, competitive time-to-market pressures dictate that troubleshooting must be completed quickly and accurately.
Getting Started To optimize your troubleshooting task at hand, it is important to start at the beginning – with proper probe compensation and attenuation, default setup, and automatic instrument setup. To properly compensate and attenuate your probe, follow these simple steps: 1. Connect the probe to channel 1. 2. Attach the probe tip and reference lead to the PROBE COMP connectors. If using the probe hook-tip, ensure a proper connection by firmly twisting the tip onto the probe.
Capture Elusive Glitches In today’s high-speed digital designs, elusive glitches and random anomalies can cause circuits to fail. While finding these glitches has never been easy, the TDS2000C Series simplifies this task with its peak detect feature. Peak detect can capture narrow glitches, even on low-frequency signals. To use the Peak Detect feature: 1. Display the waveform on the screen. 2. Press the ACQUIRE front panel menu button. 3. Press the Peak Detect menu button. 4.
Capture Elusive Glitches (continued) Intermittent signal anomalies can also be a challenge to see. The TDS2000C Series provides variable- and infinite-persistence display capabilities to provide you with information about the signal variations over time, making it easier to understand the characteristics of the transients you’ve captured. To use Display Persistence: 1. Display the waveform on the screen. 2. Press the DISPLAY front panel menu button. 3.
Debug Digital Timing Problems Digital designers need to quickly find and analyze a wide range of circuit timing problems. For example, race conditions and transients can cause circuits to perform inaccurately. The TDS2000C Series’ pulse width trigger can help troubleshoot such situations by triggering when a signal pulse width is less than, greater than, equal to or not equal to a specified pulse width. To use the pulse width trigger: 1. Press the TRIG MENU front panel button. 2.
Verify Timing Relationships Electronics engineers often need to verify that their circuits are working as designed. One of the most common types of oscilloscope measurements is timing measurements, such as pulse width, period, and frequency. The TDS2000C Series’ cursors can be used to make such measurements quickly and easily. To make timing measurements using cursors: 1. Press the CURSOR button. 2. Press the Type menu button until the Time cursor type is selected. 3. Press the Cursor 1 menu button. 4.
Check Signal Integrity Electronics engineers may discover that a wide array of unintentional electrical events will make a difference in how circuits function in the real world. To characterize these events, engineers can measure criteria such as overshoot, ringing, ground bounce, cross talk, and other signal integrity issues. The TDS2000C Series’ cursors can be used to make such measurements. To make signal integrity measurements using cursors: 1. Press the CURSOR button. 2.
Check Signal Integrity (continued) The TDS2000C Series’ automatic measurement system can also be used to make such measurements quickly and automatically. To make signal integrity measurements using automatic measurement system: 1. Press the MEASURE front panel button. 2. Press a CH1 side menu button to add an automatic measurement. 3. Press the Type side menu button until you find the desired measurement, and then press Back. 4. Repeat steps 2 and 3 to select and display up to 5 measurements. 5.
Debugging Digital System Lock-up One common cause of digital system lock-ups is an intermittent clock. The TDS2000C Series trigger system can quickly and easily identify unexpected interruptions in the clock signal. 1. Press TRIG MENU front panel button. 2. Press Type side button until Pulse is selected. 3. Press When until > is selected. 4. Using the multipurpose knob, set Pulse Width to slightly longer than the clock pulse. 5. Press –more– and press Polarity until Negative is selected. 6.
Test For The Presence of Video Signals Video technicians must perform a quick check for the presence of a video signal at different test points. If the site is in the field, technicians will need lightweight, portable test equipment gear that they can easily carry to each location. The TDS2000C Series’ video trigger features make this oscilloscope a valuable tool for these technicians. 1. Connect the video signal to the oscilloscope using proper adapters and a 75 Ω terminator, if necessary. 2.
Look for Unintentional Circuit Noise Developers need to check for unintended noise in their prototypes. However, noisy signals can be difficult to analyze in the time domain, as shown below. Engineers and technicians can use the Fast Fourier Transform (FFT) to break down signals into component frequencies, which the oscilloscope uses to display a graph of the frequency domain of a signal, as opposed to the oscilloscope’s standard time domain graph.
Look for Unintentional Circuit Noise (continued) The TDS2000C Series offers a standard FFT feature, making it an ideal tool for these identifying sources of noise in a circuit. To create FFT display: 1. Press the front panel MATH button. 2. Press the Operation menu button until FFT is selected. 3. Press the Window menu button until the Hanning window is selected, which provides the highest frequency resolution. 4.
Power Line Harmonic Analysis Power circuit designers often need to analyze the effects of their circuits on the power line. Although an ideal power supply would present a constant load on a power line, real power supply circuits do not, creating harmonics on the power line. The TDS2000C provide simple tools to measure power supply currents and analyze the harmonics on a power line. To display the power line harmonics on a current waveform: 1. Press the CH 1 MENU front panel button. 2.
Power Line Harmonic Analysis (continued) The FFT display provides a frequency-domain display of the power line signal, including the fundamental power line frequency and the harmonics at integer multiples of the fundamental frequency. The TDS2000C cursor measurements provide an easy and accurate way to analyze this complex display. 1. Press the CURSOR front panel button. 2. Press the Source side menu button until MATH is selected. 3. Press the Type side menu button until Frequency is selected. 4.
Make a Quick Pass/Fail Test of Your Device Design engineers doing validation test and debug or manufacturing engineers performing repetitive tests often need to compare live waveform signals against a know good reference signal. The TDS2000C offers quick pass/fail testing, also known as limit testing, by comparing active signals against a user defined template waveform. The oscilloscope can be set up to count both passing and failing waveforms.
Automatically Capture and Save Elusive Waveform Anomalies Engineers often spend hours trying to capture specific events or waveform anomalies. The TDS2000C offers a data logging function that allows the oscilloscope to capture signals based on userspecified trigger conditions, Multiple triggered waveforms can be recorded based on user-defined time durations, selectable in 30 minute increments up to 8 hours of total time. Waveforms are time stamped and recorded to USB device and stored in CSV file format.
Documenting Your Results with OpenChoice® Software Design engineers in the lab and technicians in the field often need to document the work they do with their oscilloscope. They can save screen images to a removable memory device and then manually copy the files to their PC. The easy-to-use OpenChoice Desktop simplifies these documentation tasks by directly transferring screen images to your PC over USB. 1. Acquire the signal. 2. Connect the oscilloscope to the PC using a USB cable. 3.
Waveform Measurements Logging A common task for engineers and technicians is to make measurements on their oscilloscope and then manually record measurements to document circuit performance variations over time. However, this is time-consuming and can lead to inconsistent quality of documentation. The easy-to-use TekXL toolbar simplifies data gathering and documentation tasks inside Excel. 1 Acquire the signal. 2. Connect the oscilloscope to the PC using a USB cable. 3.
Waveform Analysis Using NI SignalExpress™ Tektronix Edition Software Although the TDS2000C provide significant on-board analysis capabilities, there are applications where the analysis requirements are better met with PC-based applications. SignalExpress Tektronix Edition provides advanced analysis capabilities with the ease of USB plug-and-play. 1. Acquire the signal. 2. Connect the oscilloscope to the PC using a USB cable. 3. Launch the SignalExpress TE program. 4.
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