User's Guide

ThingMagic Micro Family User Guide

Review Copy 11-6-10

www.JADAKtech.com

This appendix details environmental factors that should be considered relating to reader performance and

survivability.

ElectroStatic Discharge (ESD) Considerations

Warning: The Micro antenna ports may be susceptible to damage from Electrostatic Discharge

(ESD). Equipment failure can result if the antenna or communication ports are

subjected to ESD. Standard ESD precautions should be taken during installation to

avoid static discharge when handling or making connections to the M6 reader

antenna or communication ports. Environmental analysis should also be performed

to ensure static is not building up on and around the antennas, possibly causing

discharges during operation.

ESD Damage Overview

In Micro-based reader installations where readers have failed without known cause, ESD has been found

to be the most common cause. Failures due to ESD tend to be in the Micro Power Amplifier (PA) section.

PA failures typically manifest themselves at the software interface in the following ways:

• RF operations (read, write, etc.) respond with Assert - 7F01 - indicating a fatal error. This is typically due

to the module not being able to reach the target power level due to PA damage.

• RF operations (read, write, etc.) respond with No Antenna Connected/Detected even when a known

good antenna is attached.

• Unexpected Invalid Command errors, indicating command not supported, when that command had

worked previously. A command may become unsupported when the reader, during its self-protection

routines, has returned to the bootloader to prevent any further damage. This jump to boot loader caused

by power amp damage occurs at the start of any read tag commands.

Determining that ESD is the root cause of failures is difficult because it relies on negative result

experiments, i.e., it is the lack of failure after a configuration change, rather than a positive flag wave that

identifies it as ESD. Such flag waves are sometimes available at the unpackaged transistor level under high

power microscopy. The remoteness of microscopic examination from the installed field failures is indicative

of the high cost of using such analysis methods for investigating ESD issues. Most ESD issue resolutions

use the negative result experiments to determine success.

ESD discharges come with a range of values with vaying degrees. There will be a distribution of ESD

intensities in some installations of the bare Micro that have an ESD failure problem. There may be an issue

without knowledge of a limit in the statistics of those intensities. For the bare Micro equipped with the

mitigation methods described below, there may be an occasional ESD discharge that exceeds any given

mitigation, resulting in failure. Many installations will have some upper bound on the value of ESD events

given the geometry of that installation.

Several sequential steps are recommended for a) determining ESD is the likely cause of a given group of

failures, and b) enhancing the Micro’s environment to eliminate ESD failures. The steps vary depending on

the required Micro output power in any given application.

Appendix C: Environmental Considerations