MAX3243ECAI Maxim Integrated Products, MAX3243ECAI Datasheet - Page 11

• Manufacturer Part Number: MAX3243ECAI
• Description: IC TXRX RS232 250KBPS SD 28-SSOP
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX3243ECAI

• Number Of Drivers/receivers: 3/5
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Level 4 (the highest level) of IEC1000-4-2, without the
need for additional ESD-protection components.
The major difference between tests done using the
Human Body Model and IEC1000-4-2 is higher peak
current in IEC1000-4-2, because series resistance is
lower in the IEC1000-4-2 model. Hence, the ESD with-
stand voltage measured to IEC1000-4-2 is generally
lower than that measured using the Human Body
Model. Figure 7a shows the IEEE1000-4-2 model and
Figure 7b shows the current waveform for the ±8kV
IEC1000-4-2 Level 4 ESD contact-discharge test.
The air-gap test involves approaching the device with a
charged probe. The contact-discharge method connects
the probe to the device before the probe is energized.
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.
Figure 6a. Human Body ESD Test Models
±15kV ESD-Protected, 1µA, 3.0V to 5.5V, 250kbps,
Figure 6b. Human Body Model Current Waveform
VOLTAGE
AMPERES
SOURCE
HIGH-
DC
I
P
36.8%
100%
90%
10%
CHARGE-CURRENT
LIMIT RESISTOR
0
0
R
C
t
RL
1MΩ
100pF
RS-232 Transceivers with AutoShutdown
______________________________________________________________________________________
C s
STORAGE
CAPACITOR
CURRENT WAVEFORM
R
TIME
RESISTANCE
D
DISCHARGE
1500Ω
t
DL
I r
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Machine Model
DEVICE
UNDER
TEST
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 nonpolarized
capacitors may be used. The charge pump requires
0.1µF capacitors for 3.3V operation. For other supply
voltages, refer to Table 3 for required capacitor values.
Do not use values smaller than those listed in Table 3.
Increasing the capacitor values (e.g., by a factor of 2)
reduces ripple on the transmitter outputs and slightly
reduces power consumption. 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 capacitors).
Figure 7b. IEC1000-4-2 ESD Generator Current Waveform
Figure 7a. IEC1000-4-2 ESD Test Model
___________Applications Information
VOLTAGE
SOURCE
HIGH-
DC
t r = 0.7ns to 1ns
CHARGE CURRENT
R
LIMIT RESISTOR
C
100%
50MΩ to 100MΩ
90%
10%
I
150pF
C s
30ns
STORAGE
CAPACITOR
R
RESISTANCE
DISCHARGE
D
330Ω
60ns
Capacitor Selection
DEVICE
UNDER
TEST
t
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