Board Fault finder

Are you struggling to debug the board you have in hand? Have you ever thought of an easy option to find a fault in the circuit? Even though understanding the circuit and using the manual procedure to find the fault, there are some automated systems that can do the job for you. If you are planning to The device fault locator can do the following things for you:

1. Multi-channel input for debug

2. Functional test (analog & digital devices)

3. Various logic levels

4. Short test

5. Waveform generation

6. Voltage measurement

7. Current measurement

8. Standard sequence generated to test a circuit

9. EEPROM verification

10. Complete front end GUI interface for diagnostic view

11. Basic multi meter functionality

The board fault locators gives the ability to test the desired devices/ICs for desired functionality. The devices/ICs can be tested in circuit as well as stand alone. Generally, these kind of instruments provide support for common type of digital ics available. the integrated software in the unit is very robust and supports wide range of all these test cases. The board uses a integrated variable power supply to provide all the desired power supply outputs to the board in which fault need to be found out.

Vendors that provide these devices are:

1. GSAS Micro systems

Product name: BoardMaster 8000 Plus

2. ABI electronics

SYSTEM 8 Board Fault Locator (BFL)

Thermal Imagers

Are you working on a board with temperature (components) crossing dangerous limits or reaching the thresholds? Then how do you track them? what you do to have your board safe? The one solution is to use thermal Imager. Thermal Imagers are used in the industry to mainly detect the temperature variations. Thermal Imager can be said Heat sensor. The principle of thermal imager depends on the fact that every object emits infra red radiation and the extent of emission depends on temperature. More the temperature more is the radiation. We can say that infrared radiation is the signature of temperature. Thermal Imager has the capability to capture the limited variations in temperature. Once the thermal imager collects the data it represents the data in a visual form which indicates the intensity of the temperature. Thermal Imagers add color variations based on the temperature. As commonly used, red indicates the high temperature area.

               

The basic ingredients of thermal Imager are:

• Special Optical lens
• Infrared detector (array)
• signal processing unit
• Display

The key specifications that define the thermal Imager are:

• Infrared Resolution
• Thermal Sensitivity
• Ability to create real image that is sensed
• Temperature measurement range
• Range of measurement
• Frame rate
• Detector type (Cooled/uncooled)
• Storage capability
• Battery operating time

The various vendors that provide Thermal Imagers are:

• Keysight technologies
• Fluke
• Testo
• FLIR

General facts:

• Thermal Imagers are accurate
• Generally, on board we have number of temperature sensors but they give a approximate of the value and may not always be accurate. Thermal Imagers can access any component with accurate results.
• Thermal Imagers can sense higher temperatures of  up to 1500+ degrees
• Thermal Imagers can't measure lower temperatures below 20 deg
• Greater the resolution of the sensor more the accuracy of the measurement.
• Thermal Imagers are fast and reliable
• Thermal profile is created by the signal processing unit o the thermal Imager
• If there are multiple devices in order, the thermal Imager can only catch the image of first device
• Thermal Imagers are also used for security purposes during night to catch any intruders
• Thermal Imagers are available as hand held devices
• Thermal Imagers can be used safely as they are used hand-held at a distance from the board

Battery Charging Basics - 1

There are several batteries available in the market. The classification is mainly on the battery chemistry. Several types available are Lead-Acid, Li-ion, Ni-Cd, Ni-Mh. Of these Li-ion is mostly used in the mobiles phones widely available in the market today. Some of the batteries we use in real world are rechargeable and some are non-rechargeable. There are several options available to charge these batteries as well. The below block diagram shows the generic pattern for charging the batteries:

What are the main differences between various battery types when it comes to charging:

1. Ni-Cd, NiMH are difficult to charge than Li-ion batteries. Charging in Nickel based batteries is based on the current flow through the battery. The voltage variation must only be
2. All the battery types can undergo fast as well as slow charging. Prefer not to use fast charging on NiCd, NiMH cells.
3. NiCd, NiMH must be charged from a constant current source.
4. End of charge detection happens in NiMH, NiCd as the voltage gets reduced with overcharging.
5. The batteries have a in-built thermistor to check the heat produced within the battery. this is an indicator of increase of battery temperature.
6. All the battery chemistry can be trickle charged. Trickle charging is the charging that must be applied when the battery is fully discharged.
7. Ni-Cd are not preferred in solar applications as they need constant current charging.
8. Ni-Cd batteries can charge to full capacity and beyond with less reduction in battery capacity.
9. Ni-Cd battery absorbs the heat while charging unlike other battery chemistry.
10. Li-ion batteries charging work on the constant voltage with variable current. The current variation is based on the level of battery charging.

Electromagnetic Compatibility - 1

EMI/EMC is a very big subject in electronics. It itself has a prominent place and without EMI/EMC precautions your product may not get sold in the market. In this modern world there are radiators, absorbs everywhere. To get our product withstand such an environment, your product has to comply to standards of EMI/EMC.

Most of us basically, work on Low voltage digital Electronics products. There are several standards for each of these products and one of the primary regulation is the FCC Part 15. In FCC part 15, there are several classifications of the products like A,B,C, D,E,F among which Category B corresponds to the unintended radiation. FCC Part 15 basically mentions the allowable limits of Conducted Emission and Radiated emission.

Conducted Emission -> 150 KHz to 30 MHz

Radiated emission -> 30 MHz to 40 GHz

There are test procedures defined for each and every certification and product has to undergo these certifications before being said as compliant.

Website formally Launched

Today we have launched our company website formally. Please, have a look and post your comments here.

Weblink: www.techtouchsolutions.co.in

Signal Integrity : Driver settings

Signal Integrity is a very important concern for any high speed design. The critical design factor lies in how the receiver can analyze the transmitted signal. So, when a signal is transmitted from Driver to Receiver, the transmission path should disturb the signal to least extent. Even the signal that is propagated over the channel between driver and receiver should not interfere with the other signals on the PCB. So, from the driver side, following are the main considerations that need to be taken for a flawless design:

1. Take a proper call on the drive strength that need to be applied from the driver.

The drive strength depends on the load. So, as the load increases, the drive strength must be high. Remember that load is always measured in terms of capacitance. Higher the capacitance more the load. Consider, a scenario where there is a single driver and 2 receivers, the total load can be considered as sum of the load capacitance of the 2 receivers. This can be a scenario with 2 DIMMs connected to a single processor. If sufficient drive strength is not applied from the driver the signal may decay over time and the receiver may not reliably capture the data. Consider a scenario, where the drive strength is too high, the receiver may reliably capture the data in this case but it may cause some other issues like causing unnecessary distortion on the board because of radiation.

Note: Is is always better to use a highest current drive possible from the transmitter but we have to consider that this doesn't affect other routing on the board.

2. Driver impedance versus current

For a design topology between transmitter and receiver has to work reliably, impedance matching between them is the most important thing. So, when you are trying to drive a load, the impedance of the driver is decided by interface voltage divided by current.This gives the output impedance of the driver. So, sometimes when you set the buffer to output specific current, the impedance may have to be matched in your line. So, the requirements and relation of voltage, current and line impedance are to be understood clearly.

3. IBIS models

So, the best way to determine your channel performance is to perform simulations. The simulations are done using best high speed tools available in the market. One of the example is Hyper lynx. there are other tools like Advanced design system (ADS), Sigrity, etc. Choose the tool that you can learn quickly and use it. IBIS model is a file which characterizes the buffer inside your driver. so, check the IBIS model and set your current requirements. 

4. System thresholds

Considering the system thresholds is always a critical factor in determining the performance of your system. Before using the driver and receiver in your system check the VOH,VOL, VIL, VIH and then perform a theoretical calculations to determine if both are compatible. The logic level in a system plays a crucial role. This settings can be done in the ibis model of the driver chipset.

5. Rise time and fall time

The rise time and fall time of the signal propagating between driver and receiver is very important. In the high speed signal theory, the rise time and fall time are critical. The higher the rise time and fall time the faster the signal. For these kind of signal, the slew rate will be high. In the cases where slew rate is too high, there are chances of radiation within the board. So, controlling slew rate is very important.

6. Load current

The load current plays a crucial role. When you power on the system, the load draws a instantaneous current which need to be taken care by the driver. For some interfaces, a pull-up on the line helps to drive the necessary current. But while designing the system the drive setting must be done to accommodate this current.

Design Query

What kind of LEDs should we use for back lighting?

LEDs are of different types - Diffused, Non-diffused, Water Clear, Tinted Clear. For back lighting use only Non-diffused type. non-diffused type helps light concentrate in a narrow beam and make them appear brighter. diffused LED distributes light over wider beam and is not suitable for back lighting.