MAX3097 MAXIM [Maxim Integrated Products], MAX3097 Datasheet - Page 9

• Manufacturer Part Number: MAX3097
• Manufacturer: MAXIM [Maxim Integrated Products]

Triple RS-422/RS-485 Receivers with Fault Detection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against ESD
encountered during handling and assembly. The
MAX3097E/MAX3098E receiver inputs have extra pro-
tection against static electricity found in normal opera-
tion. Maxim’s engineers developed state-of-the-art
structures to protect these pins against ±15kV ESD
without damage. After an ESD event, the MAX3097E/
MAX3098E continue working without latchup.
ESD protection can be tested in several ways. The
receiver inputs are characterized for protection to the
following:
• ±15kV using the Human Body Model
• ±8kV using the Contact Discharge method specified
• 15kV using the Air-Gap Discharge method specified
ESD performance depends on a number of conditions.
Contact Maxim for a reliability report that documents
test setup, methodology, and results.
Figure 5a shows the Human Body Model, and Figure
5b 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 device through a
1.5kΩ resistor.
Figure 5a. Human Body ESD Test Model
in IEC 1000-4-2 (formerly IEC 801-2)
in IEC 1000-4-2 (formerly IEC 801-2)
VOLTAGE
SOURCE
HIGH-
DC
CHARGE-CURRENT
LIMIT RESISTOR
1MΩ
R
C
100pF
C s
_______________________________________________________________________________________
STORAGE
CAPACITOR
RESISTANCE
DISCHARGE
1.5k
R
±15kV ESD Protection
D
±15kV ESD-Protected, 32Mbps, 3V/5V,
ESD Test Conditions
Human Body Model
DEVICE
UNDER
TEST
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 MAX3097E/MAX3098E help you
design equipment that meets Level 4 (the highest level)
of IEC 1000-4-2, without additional ESD-protection com-
ponents.
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 6a), the
ESD-withstand voltage measured to this standard is gen-
erally lower than that measured using the Human Body
Model. Figure 6b 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.
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. 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.
Figure 5b. Human Body Model Current Waveform
AMPERES
I
P
36.8%
100%
90%
10%
0
0
t
RL
CURRENT WAVEFORM
TIME
t
DL
I r
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Machine Model
IEC 1000-4-2
9