Avoiding Damage to Your DAS

When working with DTS DAS, there are a number of actions/events to avoid that will help to minimize the chance of causing damage to your system during use/setup.

Power Input Concerns:

• Power supply reliability for over-voltage protection (OVP), ESD, current paths, etc.
• Avoid inadvertent positive-line grounding events on the power source.
  • Powering with battery packs (car/bike/etc.) is especially subject to grounding issues.  Review hookup VERY carefully before powering.
• Backup power supplies should be carefully reviewed and configured to ensure there are not grounding/cross voltage issues.

Sensor Input Concerns:

• Safe Input Voltage Range:  Make sure your input voltage ranges for everything from your power supply source to your test signals fall within your system's safe input voltage range.  This can be found on your device's datasheet.
• Common Mode Voltage Range:  Make sure that input voltage ranges for test signals adhere to the common mode voltage range listed on the datasheet.  For most systems, this will be within the +/-2.5 V or 0-4.9 V range.  If your desired test signal exceeds this range, use a voltage range expander cable/circuit to allow for safe interface with the DAS.
• All DTS DAS contain Transient Voltage Supression (TVS) devices on the inputs.  They are specifically designed to protect the DAS for high voltage transient signals so a prolonged signal over the rated safe input voltage will damage these TVS's and the DAS channel. This damage often becomes apparent when diagnostics is next run on the DAS and the channel will be clamped to the power rail resulting in a high sensor offset that cannot be removed.
• ESD Protection:  When working with electronic systems, follow ESD protection guidelines to limit the chances of spurious events.  SAE J211 has an appendix which provides some best practices regarding this.

Hot-Swapping Conditions:

• Do not engage in hot-swapping of cables/connectors.  Hot-swapping is the plug-in/removal of cables/connectors that are powered/experiencing input.  All connection events should take place with all related systems unpowered.
• Engaging in changing DAS configurations can cause excess current events, etc.
• In specific relation to the SLICE NANO and SLICE MICRO systems which are often embedded with custom wiring, please be sure that if you make your own USB wiring that any connector has a leading edge ground pin that connects before any other USB comm pin.  The low power USB chip in these devices is particularly susceptible to ESD damage.

Grounding Concerns:

• Avoid ground loops.  They can cause unwanted high current conditions.
• Adhere to proper grounding practices which can help avoid ESD or electromagnetic environment damage.

Connectors/Connections to the DAS

• Avoid excessive 'jiggling' or 'twisting' of cables and connectors going to/from the DAS, as these actions can loosen wires and/or bend pins on connectors to create disconnect/short conditions.
• Try to route power wiring away from sensor wiring as much as possible.  If it has to cross, try to make them cross at a 90 degree angle while maintaining as much separation as possible to avoid any induced EMF (Faraday's Law). 

 If you think you've damaged your DAS, here are some signs to look for:

• Does it smell/look burned at any of the connectors?
• Is there obvious physical damage to the unit (connectors, cables, body, etc.)?
• Do the LED lights cycle through the power up sequence when connecting the unit to a power source?  (See User's Manual for specifics on the power-up LED sequence.)
• Does the power source supply go into OVP or over-current protection (OCP) mode when attempting to power the unit?