Figure 3b. Human Body Current Waveform
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures are
incorporated on all pins to protect against electrostatic
discharges encountered during handling and assembly.
The I/O V
CC
lines have extra protection against static
electricity. Maxim’s engineers have developed state-of-
the-art structures to protect these pins against ESD of
±15kV without damage. The ESD structures withstand
high ESD in all states: normal operation, three-state
output mode, and powered down. After an ESD event,
Maxim’s E versions keep working without latchup,
whereas competing products can latch and must be
powered down to remove latchup.
ESD protection can be tested in various ways. The I/O
V
CC
lines of this product family are characterized for
protection to the following limits:
1) ±15kV using the Human Body Model
2) ±8kV using the Contact Discharge method specified
in IEC 1000-4-2
3) ±10kV using IEC 1000-4-2’s Air-Gap Discharge
method
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results.
Human Body Model
Figure 3a shows the Human Body Model and Figure 3b
shows the current waveform it generates when dis-
charged into a low impedance. This model consists of
a 100pF capacitor charged to the ESD voltage of inter-
est, which is then discharged into the test device
through a 1.5kΩ resistor.
IEC 1000-4-2
The IEC 1000-4-2 standard covers ESD testing and
performance of finished equipment; it does not specifi-
cally refer to integrated circuits. The MAX3372E–
MAX3379E and MAX3390E–MAX3393E help to design
equipment that meets Level 3 of IEC 1000-4-2, without
the need for additional ESD-protection components.
The major difference between tests done using the
Human Body Model and IEC 1000-4-2 is higher peak
current in IEC 1000-4-2, because series resistance is
lower in the IEC 1000-4-2 model. Hence, the ESD with-
stand voltage measured to IEC 1000-4-2 is generally
lower than that measured using the Human Body Model.
Figure 4a shows the IEC 1000-4-2 model, and Figure 4b
shows the current waveform for the ±8kV, IEC 1000-4-2,
Level 4, ESD contact-discharge test.
The air-gap test involves approaching the device with a
charged probe. The contact-discharge method con-
nects the probe to the device before the probe
is energized.
Machine Model
The Machine Model for ESD tests all pins using a
200pF storage capacitor and zero discharge resis-
tance. Its objective is to emulate the stress caused by
contact that occurs with handling and assembly during
manufacturing. Of course, all pins require this protec-
tion during manufacturing, not just inputs and outputs.
Therefore, after PCB assembly, the Machine Model is
less relevant to I/O ports.
