Electrical overstress

Under the technical term English Electrical Over Stress , abbreviated EOS in is Electronics an overload during operation and as a result thermal destruction associated predamage or electronic components such as integrated circuits (IC), understood.

Demarcation

Thermally destroyed IC package according to EOS

An EOS event must be differentiated from an electrostatic discharge (ESD) event based on the amount of energy: ESD discharges are characterized by high electrical voltages and short discharge times in the range of a few microseconds, but little energy is converted in comparison to an EOS. In the event of an EOS event, in certain cases associated with visually recognizable thermal damage to the chip housing , a multiple of the amount of energy is converted. The electrical overstress differs from the latch-up effect , since there are no parasitic short circuits in the structure of the electronic components as the cause.

EOS events are characterized by overloads and exceeding electrical limit values, such as the maximum permissible voltage or current values, in regular operation. The exceedances occur briefly, for example when an electronic device is switched on, and can also be only a few 10% above the permissible limit values. The duration of the effect of EOS events fluctuates and is in the range from a few milliseconds to fractions of a second, the energy for the destruction comes from the power supply provided for regular operation .

causes

EOS can be triggered by a wide variety of causes. In addition to systematic errors such as incorrectly dimensioned electronic circuits in the values, the causes can include:

Effects of direct and indirect lightning discharges and inadequate lightning protection .
Overvoltages and voltage fluctuations in power grids and insufficient compensation of these disturbances in electronic devices.
Settling processes in power supplies when switching on when switching on. This mainly affects switching power supplies .
When switching electromechanical components with high inductivity, such as relays or electric motors, without taking precautions against overvoltages caused by self-induction .
If there are several different operating voltages, a wrong sequence when switching these different voltages on and off. In possible combination with the failure of one of these voltages.

prevention

EOS cannot be completely prevented, but the effects can be minimized by design measures such as additional protective circuits in the form of overvoltage protection in electronic devices and in the structure of the integrated circuits. Furthermore, similar to the protection against unwanted electrostatic discharges, there is the possibility of reducing the occurrence of destructive EOS through appropriate behavior. For example, in the case of interfaces and plug connections that are not designed for plugging and unplugging during operation, so-called hot-plug , the electronic device should be switched off before plugging and unplugging.

literature

Steven H. Voldman: Electrical Overstress (EOS): Devices, Circuits and Systems . John Wiley & Sons, 2013, ISBN 978-1-118-70333-5 .

Individual evidence

^ Electrical Overstress EOS. Cypress Semiconductor, corporate publication, 2010, accessed May 2, 2017 .
↑ Steven H. Voldman: Electrical Over Stress (EOS): Devices, Circuits and Systems . John Wiley & Sons, 2013, ISBN 978-1-118-70333-5 , Chapter 3.1: Electrical Overstress Sources.

[cypr1-1] Electrical Overstress EOS. Cypress Semiconductor, corporate publication, 2010, accessed May 2, 2017 .

[vold1-2] Steven H. Voldman: Electrical Over Stress (EOS): Devices, Circuits and Systems . John Wiley & Sons, 2013, ISBN 978-1-118-70333-5 , Chapter 3.1: Electrical Overstress Sources.