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Q&A
Homepage / Q&A
Thermography Eases Prototype Test for PCBA Development
- Q: Does Thermal imager works by emitting infrared radiation, and receive the reflected signal to form the infrared thermal image?
- A: No, it does not emit any infared radiation, it receives infrared radiation.
- Q: Possible to install this tester as online inspection tool in production line?
- A: The online monitoring thermal imager from Fluke's subsidy ¨C Raytek allows up to 64 "Area of Interest" to be created and monitored. It is possible for user to learn the thermal profile from a few known good boards, then divide the PCB assembly into several zones (up to 64 zones maximum) and specify the maximum / minimum temperature limits for each and very zone.
- Q: Apart from using thermal imager on electrical and electronic components can I use it on mechanical, building applications and energy auditing like energy leakages from air-con or heating system?
- A: Yes, it can. On mechanical like bearings temperature and machine heat profile. Building water seepage analysis and heat or air-conditional leaks of doors or window in a building etc.. There are many applications for Thermal imaging.
Use IR Thermography to Speed Profiling of Electronic Circuits in Enclosures
- Q: Is it difficult to use the thermal imager?
- A: No it is not. Our Thermal imager comes with only 3 buttons and a trigger. If you are able to handle a compact camera you will be able to handle our thermal imager.
- Q: Can the thermal imager be tripod mounted?
- A: Yes, we do have accessories for you to mount our imager on a tripod.
- Q: "fluke" has manufacture IR thermography use for check human body?
- A: Yes, you can use the Thermal imager to check on human temperature.
National Semiconductor SIMPLE SWITCHERŽ Power Module and Easy to Use Design Tool
- Q: What is limiting the load current on my LM2678 evaluation board?
- A: If the LM2678 evaluation board cannot deliver the full rated load current of 5A, the input ceramic capacitor may be too far away from switcher input pin. It needs to be as close as is physically possible to the Vin and Ground pins, with wide, short traces.
- Q: What is "On/Off" or "Shutdown" on a regulator?
- A: An On/Off or Shutdown feature allows the regulator to be turned on or off while power is applied to its input. While in the Off or Shutdown mode, the regulator's supply current drops to a low level as the output stage is disabled but the internal bias circuitry is still operational. When turned On again, the regulator regains regulation of the output voltage much more quickly than it would if the input supply voltage had been switched off then on. If there is a bar shown over the "Off" part of On/Off or over "Shutdown", the regulator is turned on with a logic high. Otherwise, a logic low enables the regulator.
- Q: When using an LM2675 to provide 5V power for a lamp which blinks at 1Hz, drawing 250mA, the regulator goes into discontinuous mode when the lamp is off. When the lamp turns on, the 5V rail sometimes dips 2V for 100ms before "catching back up." Why? Would applying a minimum load fix the problem?
- A: When the load is removed, such as when the lamp blinks off, the LM2675 goes into discontinuous mode because of the zero amp load current. Since it takes 1 second for the lamp in your application to blink ON, the energy previously stored in the capacitor is discharged through the catch diode. On reapplication of the load, it takes time for the output voltage to ramp up, which explains the transient dip of approximately 100ms you observed. A resistive load drawing a minimum of 20mA should suffice to maintain the specified load regulation.
Overcoming the Electrical Measurement Challenges of High Brightness LEDs
- Q: How is the turn on voltage determined?
- A: The turn on voltage is determined by sweeping the voltage of the LED from 0V up to a voltage in which a preselected amount of current begins to flow. For example, the LED is swept until 1mA of current begins to flow. At what current level the LED is considered On is determined by the manufacturer.
- Q: Can this method be used for tri-colored leds?
- A: I assume you are refering to the measuring junction temperature from forward voltage method. In a tri color LED, each individual color will have it's own anode. This method can be used on each anode individually however, the m and T0 values for for one anode will not apply to the others. Each one must be characterized seperately.
- Q: which device you would recommend for ac led test?
- A: Hello, In "device" do you mean which type of instrumentation to source and/or measure?
Tips, Tricks, and Traps in Ultra-Fast I-V Semiconductor Characterization
- Q: So these are my four questions-: 1)Maximum voltage and frequency limits for pulsed I-V measurements in 4200 SCS? 2)How can we increase the voltage level if we need to give a pulse of 80V at a frequency of micro-secs. 3)What is the change in circuit for measuring current in all three arms of a transistor 4)What is the experimental set up for a 4-terminal FET structure. Please mail the answers to my mail id -:satya2687@gmail.com
- A: 1) Max V = 40V. Max frequency depends on other settings, but could be 33MHz. 2) One way to increase voltage level is to use an external bias tee and voltage source. The Keithley 4200-PIV-Q uses this to supply up to 80V at 500ns. 3) To measure current in all three arms you need three channels of Ultra-Fast IV. The 4225-PMU will do this (up to 8 channels) but the PIV-Q (80V) will not. 4) For 4 terminal device, you either connect the gate and drain to source/measure channels, and ground the source and bulk), or you connect all four terminals to source/measure channels.
- Q: Again for the phase change RAM (changing from 1e4 to 1e6 ohm). I'm measuring the DUT via a AFM conductive tip (20 nm diameter at the end). In what extent does this affect the shape of the pulse since it's not 50 ohm adapted to the rest of the signal path?
- A: Good Question! The real impact in this case is the residual capacitance in the probe system, not the transmission line impedance. The voltage on the device will behave, the current through the device will vary based on residual capacitance.
- Q: Our intention is to measure Light output and Voltage drop of LEDs and VCSELs. It is possible to get two or more channels triggert and measure voltage drop over DUT and Light output (Front and Backside) simultanously..?
- A: Up to 8 channels can measure simultaneously, with sub 5ns syncronization.
Understanding the Basics of Electrical Measurements
- Q: I would like to know if there are instruments I can use to calibrate (determin it's responsivity curve) a photodiode? Thank you
- A: Hello Evelyne - Keithley can provide the appropriate equipment for, say, measuring the current output of the photodiode, but we do not supply any equipment to stimulate the photodiode with light. In otherwords you could sweep a light source from dark to light, and characterise the current flowing through the photdiode. Keithley has a range of Sourcemeters, which combine sourcing voltage or current, and measuring voltage or current. These are used extensively in R&D and industry for this type of application. The 2400, or 2600 series should be suitable. --Derek
- Q: Does guarding help with low voltage measurements?
- A: Guarding is typically associated with high-resistance/low current measurements. As rule of thumb, you should use guarding when your device resistance approaches 1 gigohm or higher, or the test currents involved approach 1nA or less. If you are using low voltages with high-resistance then the use of guarding would certainly be appropriate.
- Q: Can you truely eliminate all lead resistance with a 4 wire system?
- A: You will "sense around" all lead resistance up to the points where your force and sense leads come together. For example, assume that your force HI and Sense HI leads come together at a single pogo pin or sharp probe. The LO leads are connected similarly to another pin or probe. You will completely sense around the reistance of both the HI and LO force leads, but the resistance of the actual pins or probes will be included in your measurements.
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