_______________Detailed Description
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electro-
static discharges (ESD) encountered during handling
and assembly. The MAX3095/MAX3096 receiver inputs
have extra protection against static electricity found in
normal operation. Maxim’s engineers developed state-
of-the-art structures to protect these pins against ±15kV
ESD, without damage. After an ESD event, the MAX3095/
MAX3096 continue working without latchup.
ESD protection can be tested in several ways. The
receiver inputs are characterized for protection to the
following:
1) ±15kV using the Human Body Model
2) ±8kV using the Contact-Discharge Method specified
in IEC 1000-4-2 (formerly IEC 801-2)
3) ±15kV using the Air-Gap Method specified in
IEC 1000-4-2 (formerly IEC 801-2)
ESD Test Conditions
ESD performance depends on a number of conditions.
Contact Maxim for a reliability report that documents
test setup, methodology, and results.
Human Body Model
Figure 4a shows the Human Body Model, and Figure
4b 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 interest,
which is then discharged into the device through a
1.5kΩ resistor.
IEC 1000-4-2
Since January 1996, all equipment manufactured and/or
sold in the European community has been required to
meet the stringent IEC 1000-4-2 specification. The IEC
1000-4-2 standard covers ESD testing and performance
of finished equipment; it does not specifically refer to inte-
grated circuits. The MAX3095/MAX3096 help you design
equipment that meets Level 4 (the highest level) of IEC
1000-4-2, without additional ESD-protection components.
The main 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 ESD test model (Figure 5a), the
ESD-withstand voltage measured to this standard is gen-
erally lower than that measured using the Human Body
Model. Figure 5b 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
charge probe. The Contact-Discharge method connects
the probe to the device before the probe is energized.
Machine Model
The Machine Model for ESD testing uses a 200pF stor-
age capacitor and zero-discharge resistance. It mimics
the stress caused by handling during manufacturing
and assembly. Of course, all pins (not just RS-485
inputs) require this protection during manufacturing.
Therefore, the Machine Model is less relevant to the I/O
ports than are the Human Body Model and IEC 1000-4-2.
Low-Power Shutdown Mode
Table 1 shows the functionality of the enable inputs.
The MAX3095/MAX3096 enter shutdown when G is low
and G is high. In shutdown, all outputs go high imped-
ance and the devices typically draw less than 1nA. The
devices exit shutdown by taking G high or G low. The
typical shutdown exit time is 600ns.
MAX3095/MAX3096
±15kV ESD-Protected, 10Mbps, 3V/5V,
Quad RS-422/RS-485 Receivers
Table 1. Function Table
OUTPUT
Y
DEVICE
MODE
G
G
(A - B)
On
1 X ≥ 200mV 1 On
1 X ≤ -200mV 0
1 X Open 1 On
X 0 ≥ 200mV 1 On
X 0 ≤ -200mV 0 On
X 0 Open 1 On
0 1 X High-Z Shutdown
X = don’t care, High-Z = high impedance
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