AN10E40 Data Manual
29
Discharge to the Device
An ESD event can occur when any charged conductor (including the human body) discharges to an ESDS
(electrostatic discharge sensitive) device. The most common cause of electrostatic damage is the direct transfer of
electrostatic charge from the human body or a charged material to the electrostatic discharge sensitive (ESDS)
device. When one walks across a floor, an electrostatic charge accumulates on the body. Simple contact of a finger
to the leads of an ESDS device or assembly allows the body to discharge, possibly causing device damage. The
model used to simulate this event is the Human Body Model (HBM).
A similar discharge can occur from a charged conductive object, such as a metallic tool or fixture. The model used
to characterize this event is known as the Machine Model.
Discharge from the Device
The transfer of charge from an ESDS device is also an ESD event. The trend towards automated assembly would
seem to solve the problems of HBM ESD events. However, it has been shown that components may be more
sensitive to damage when assembled by automated equipment. A device may become charged, for example, from
sliding down the feeder. If it then contacts the insertion head or another conductive surface, a rapid discharge
occurs from the device to the metal object. This event is known as the Charged Device Model (CDM) event, and
can be more destructive than the HBM for some devices. Although the duration of the discharge is very short--often
less than one nanosecond--the peak current can reach several tens of amperes.
Field Induced Discharges
Another event that can directly or indirectly damage devices is termed Field Induction. As noted earlier, whenever
any object becomes electrostatically charged, there is an electrostatic field associated with that charge. If an ESDS
device is placed in that electrostatic field, a charge may be induced on the device. If the device is then momentarily
grounded while within the electrostatic field, a transfer of charge from the device occurs.
AN10E40 ESD Classifications
Pin Type
Classifications
Class 2
Notes
Digital Inputs
M4 and C6 classifications are based
on estimated performance based on
extensive HBM characterization.
M4 and C6 classifications are based
on estimated performance based on
extensive HBM characterization.
M4 and C6 classifications are based
on estimated performance based on
extensive HBM characterization.
M4 and C6 classifications are based
on estimated performance based on
extensive HBM characterization.
M4 and C6 classifications are based
on estimated performance based on
extensive HBM characterization.
Class M4
Class C6
Class 2
Digital Outputs
Class M4
Class C6
Class 2
Digital I/0
Class M4
Class C6
Class 2
Analog I/0
Class M4
Class C6
Class 2
CEXT, OPAMVMR, VMR, VREF
Class M4
Class C6
LATTICE [ LATTICE SEMICONDUCTOR ]
