MAX13080E Datasheet, PDF (17/24 Pages) Maxim Integrated Products – +5.0V, 15kV ESD-Protected, Fail-Safe, Hot-Swap, RS-485/RS-422 Transceivers

+5.0V, ±15kV ESD-Protected, Fail-Safe,
Hot-Swap, RS-485/RS-422 Transceivers
R_C
R_D
1MΩ
1500Ω
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
HIGH-
VOLTAGE
DC
SOURCE
Cs
100pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
R_C
50MΩ TO 100MΩ
R_D
330Ω
CHARGE-CURRENT-
LIMIT RESISTOR
DISCHARGE
RESISTANCE
HIGH-
VOLTAGE
DC
SOURCE
Cs
150pF
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 10a. Human Body ESD Test Model
Figure 10c. IEC 61000-4-2 ESD Test Model
I_P 100%
90%
Ir
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
AMPS
36.8%
10%
0
0 _tRL
TIME
t_DL
CURRENT WAVEFORM
Figure 10b. Human Body Current Waveform
I
100%
90%
10%
tr = 0.7ns TO 1ns
30ns
t
60ns
Figure 10d. IEC 61000-4-2 ESD Generator Current Waveform
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 IEC 61000-4-2 ESD
Contact Discharge test.
Machine Model
The machine model for ESD tests all pins using a
200pF storage capacitor and zero discharge resis-
tance. The objective is to emulate the stress caused
when I/O pins are contacted by handling equipment
during test and assembly. Of course, all pins require
this protection, not just RS-485 inputs and outputs.
Applications Information
256 Transceivers on the Bus
The standard RS-485 receiver input impedance is 12kΩ
(1-unit load), and the standard driver can drive up to 32-
unit loads. The MAX13080E family of transceivers has 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,
as well as other RS-485 transceivers with a total of 32-
unit loads or fewer, can be connected to the line.
Reduced EMI and Reflections
The MAX13080E/MAX13081E/MAX13082E feature
reduced slew-rate drivers that minimize EMI and
reduce reflections caused by improperly terminated
cables, allowing error-free data transmission up to
250kbps. The MAX13083E/MAX13084E/MAX13085E
offer higher driver output slew-rate limits, allowing
transmit speeds up to 500kbps. The MAX13089E with
SRL = V_CC or unconnected are slew-rate limited. With
SRL unconnected, the MAX13089E error-free data
transmission is up to 250kbps. With SRL connected to
V_CC, the data transmit speeds up to 500kbps.
______________________________________________________________________________________ 17