MAX3229EEBV MAXIM [Maxim Integrated Products], MAX3229EEBV Datasheet - Page 10

• Manufacturer Part Number: MAX3229EEBV
• Manufacturer: MAXIM [Maxim Integrated Products]

The IEC 1000-4-2 standard covers ESD testing and per-
formance of finished equipment; it does not specifically
refer to integrated circuits. The MAX3228E/MAX3229E
help you design equipment that meets Level 4 (the high-
est level) of IED 1000-4-2, without the need for addition-
al ESD-protection components.
The major difference between tests done using the
Human Body Model and IEC 1000-4-2 is a 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 6a shows the IEC 1000-4-2 model, and 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
charged probe. The Contact Discharge method con-
nects the probe to the device before the probe is ener-
gized.
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP
Figure 6a. IEC 1000-4-2 ESD Test Model
Figure 6b. IEC 1000-4-2 ESD Generator Current Waveform
10
VOLTAGE
SOURCE
HIGH-
t r = 0.7ns to 1ns
DC
_____________________________________________________________________________________
CHARGE-CURRENT
R
LIMIT RESISTOR
100%
C
90%
10%
50MΩ to 100MΩ
I
150pF
C s
30ns
STORAGE
CAPACITOR
R
RESISTANCE
DISCHARGE
D
60ns
330Ω
IEC 1000-4-2
DEVICE
UNDER
t
TEST
The Machine Model for ESD tests all pins using a 200pF
storage capacitor and zero discharge resistance. Its
objective is to emulate the stress caused by contact that
occurs with handling and assembly during manufactur-
ing. Of course, all pins require this protection during
manufacturing, not just RS-232 inputs and outputs.
Therefore, after PC board assembly, the Machine Model
is less relevant to I/O ports.
The capacitor type used for C1–C4 is not critical for
proper operation; either polarized or non polarized
capacitors may be used. However, ceramic chip
capacitors with an X7R or X5R dielectric work best. The
charge pump requires 0.1µF capacitors for 3.3V opera-
tion. For other supply voltages, refer to Table 4 for
required capacitor values. Do not use values smaller
than those listed in Table 4. Increasing the capacitor
values (e.g., by a factor of 2) reduces ripple on the
transmitter outputs and slightly reduces power con-
sumption. C2, C3, and C4 can be increased without
changing C1’s value. However, do not increase C1
without also increasing the values of C2, C3, and C4
to maintain the proper ratios (C1 to the other capac-
itors).
When using the minimum required capacitor values,
make sure the capacitor value does not degrade
excessively with temperature. If in doubt, use capaci-
tors with a larger nominal value. The capacitor’s equiv-
alent series resistance (ESR) usually rises at low
temperatures and influences the amount of ripple on
V+ and V-.
In most circumstances, a 0.1µF V
is adequate. In applications that are sensitive to power-
supply noise, use a capacitor of the same value as the
charge-pump capacitor C1. Connect bypass capaci-
tors as close to the IC as possible.
Table 4. Required Capacitor Values
2.5 to 3.0
3.0 to 3.6
4.5 to 5.5
3.0 to 5.5
V
CC
(V)
Applications Information
C1, C
Power-Supply Decoupling
BYPASS
0.047
0.22
0.22
0.1
Capacitor Selection
(µF)
CC
bypass capacitor
Machine Model
C2, C3, C4 (µF)
0.22
0.33
0.1
1