ADM485E AD [Analog Devices], ADM485E Datasheet - Page 14

• Manufacturer Part Number: ADM485E
• Manufacturer: AD [Analog Devices]

ADM485E/ADM487E/ADM1487E
ESD Testing
Two coupling methods are used for ESD testing: contact
discharge and air-gap discharge. Contact discharge calls for
a direct connection to the unit being tested; air-gap discharge
uses a higher test voltage but does not make direct contact with
the unit under test. With air discharge, the discharge gun is moved
toward the unit under test, developing an arc across the air gap;
hence the term air discharge. This method is influenced by
humidity, temperature, barometric pressure, distance, and rate
of closure of the discharge gun. The contact-discharge method,
though less realistic, is more repeatable and is gaining accep-
tance and preference over the air-gap method.
Although very little energy is contained within an ESD pulse,
the extremely fast rise time, coupled with high voltages, can
cause failures in unprotected semiconductors. Catastrophic
destruction can occur immediately as a result of arcing or heating.
Even if catastrophic failure does not occur immediately, the
device can suffer from parametric degradation, which can result
in degraded performance. The cumulative effects of continuous
exposure can eventually lead to complete failure.
I/O lines are particularly vulnerable to ESD damage. Simply
touching or plugging in an I/O cable can result in a static
discharge that can damage or completely destroy the inter
face product connected to the I/O port. It is, therefore, extremely
important to have high levels of ESD protection on the I/O lines.
ESD TEST METHOD
HUMAN BODY MODEL
GENERATOR
VOLTAGE
HIGH
Figure 27. ESD Generator
C1
R2
±15kV
R2
UNDER TEST
DEVICE
C1
100pF
Rev. 0 | Page 14 of 16
The ESD discharge can induce latch-up in the device under test.
Therefore, it is important that ESD testing on the I/O pins be
carried out while device power is applied. This type of testing
is more representative of a real-world I/O discharge where the
equipment is operating normally when the discharge occurs.
Table 9. ADM483E ESD Test Results
ESD Test Method
Human Body Model (HBM)
36.8%
100%
90%
10%
Figure 28. Human Body Model ESD Current Waveform
t
RL
t
DL
I/O Pins
±15 kV
TIME (
Other Pins
±3.5 V
t
)