March 1, 2020

JTAG Test Can Eliminate the “Ground Bounce” Effect

Flynn Systems Corporation

When large numbers of outputs switch simultaneously, they can cause intermittency with your test due the ground bounce effect. JTAG Test with onTAP lets you control this problem by giving you control over how many outputs switch during a single test scan, as shown below:

Understanding ground bounce

In manufacturing test environments, it’s not uncommon for several users to run tests at the same time.  From onTAP tests to cluster tests and flash programming, without the proper measures in place you may be facing “ground bounce.”

This phenomenon is associated with transistor switching where the gate voltage can appear to be less than the local ground potential, causing the unstable operation of a logic gate. Logic gates are physical electronic devices that perform logical functions on one or more binary inputs.

The effects of ground bounce

Ground bounce is one of the main causes of metastable gates in circuit design.  This occurs because of the inputted voltage levels are incorrect for the board design, or has poorly designed ground paths.  When this occurs, base voltage may go negative causing the transistor to shut down.

If you’re experiencing ground bounce, it’s time to contact our team at Flynn Systems.  We provide an exceptional JTAG test that surpasses any solution available.  For more information call today at (603) 598-4444.

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Flynn Systems Corporation

March 1, 2020