MAX13181E Datasheet, PDF (12/18 Pages) Maxim Integrated Products – +5.0V, ±15kV ESD-Protected, Half-Duplex/Full-Duplex, RS-485 Transceiver in uDFN

+5.0V, ±15kV ESD-Protected, Half-Duplex/
Full-Duplex, RS-485 Transceiver in µDFN
R_C
1MΩ
R_D
1500Ω
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
HIGH-
VOLTAGE
DC
SOURCE
Cs
100pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
I_P 100%
90%
AMPS
36.8%
10%
0
0 _tRL
Ir
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
TIME
t_DL
CURRENT WAVEFORM
Figure 7a. Human Body ESD Test Model
Figure 7b. Human Body Current Waveform
R_C
50MΩ TO 100MΩ
R_D
330Ω
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
I
100%
90%
HIGH-
DEVICE
VOLTAGE
Cs
STORAGE
UNDER
DC
150pF
CAPACITOR
TEST
SOURCE
10%
tr = 0.7ns TO 1ns
30ns
t
60ns
Figure 7c. IEC 1000-4-2 ESD Test Model
Human Body Model
Figure 7a shows the Human Body Model, and Figure 7b
shows the current waveform it generates when discharged
into a low impedance. This model consists of a 100pF
capacitor charged to the ESD voltage of interest, which is
then discharged into the test device through a 1.5kΩ resistor.
Machine Model
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. However, it does
not specifically refer to integrated circuits. The
MAX13485E/MAX13486E help equipment designs to
meet IEC 61000-4-2, without the need for additional
ESD protection components.
The major difference between tests done using the
Human Body Model and IEC 61000-4-2 is higher peak
current in IEC 61000-4-2 because series resistance is
lower in the IEC 61000-4-2 model. Hence, the ESD with-
stand voltage measured to IEC 61000-4-2 is generally
lower than that measured using the Human Body
Model. Figure 10c shows the IEC 61000-4-2 model, and
Figure 10d shows the current waveform for the IEC
61000-4-2 ESD Contact Discharge test.
Figure 7d. IEC 1000-4-2 ESD Generator Current Waveform
Applications Information
256 Transceiver on the Bus
The standard RS-485 receiver input impedance is 12kΩ
(one-unit load), and the standard driver can drive up to 32
unit loads. The MAX13181E–MAX13184E family trans-
ceivers have a 1/8-unit load receiver input impedance
(96kΩ), allowing up to 256 transceivers to be connected
in parallel on one communication line. Any combination of
these devices and/or other RS-485 transceivers with a
total of 32 unit loads or less can be connected to the line.
Reduced EMI and Reflections
The MAX13181E/MAX13182E are slew-rate limited, min-
imizing EMI and reducing reflections caused by improp-
erly terminated cables. This slew-rate limited feature
allows error-free data transmission up to 250kbps.
MAX13181E/MAX13183E Low-Power
Shutdown Mode
The MAX13181E/MAX13183E feature low power shut-
down mode. Low-power shutdown mode is initiated by
bringing RE high and DE low. In shutdown, the devices
typically draw only 2.5µA (typ) of supply current. RE
and DE can be driven simultaneously. If RE is high and
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