MAX14770E_13 Datasheet, PDF (14/16 Pages) Maxim Integrated Products – High-ESD Profibus RS-485 Transceiver

MAX14770E
High-ESD Profibus RS-485 Transceiver
DI
D
DE
RO
R
RE
120I
B
A
B
A
120I
B
B
A
A
MAX14770E
R
D
R
D
DI
DE RO RE
Figure 12. Typical Half-Duplex RS-485 Network
DI
DE RO RE
DE
D
DI
R
RO
RE
RC
1MI
CHARGE-CURRENT-
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
SOURCE
CS
100pF
RD
1.5kI
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
Figure 13. Human Body ESD Test Model
IP 100%
90%
AMPERES
36.8%
10%
0
0 _tRL
IR
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
TIME
t_DL
CURRENT WAVEFORM
Figure 14. Human Body Current Waveform
Extended ESD Protection
ESD protection structures are incorporated on all pins
to protect against electrostatic discharges up to Q2kV
(HBM) encountered during handling and assembly.
A and B are further protected against high ESD up
to Q35kV (HBM) without damage. The A and B pins
are also protected against Q20kV Air-Gap and Q10kV
Contact IEC61000-4-2 ESD events. The ESD structures
withstand high ESD both in normal operation and when
the device is powered down. After an ESD event, the
MAX14770E continues to function without latchup.
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents test
setup, test methodology, and test results.
Human Body Model
Figure 13 shows the HBM. Figure 14 shows the current
waveform it generates when discharged into a low-
impedance state. This model consists of a 100pF capaci-
tor charged to the ESD voltage of interest that is then
discharged into the device through a 1.5kI resistor.
IEC 61000-4-2
The IEC 61000-4-2 standard covers ESD testing and
performance of finished equipment. It does not spe-
cifically refer to integrated circuits. The MAX14770E
is specified for Q20kV Air-Gap Discharge and Q10kV
Contact Discharge IEC 61000-4-2 on the A and B pins.
The main difference between tests done using the HBM
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
14  
Maxim Integrated