ADUM1100ARWZ AD [Analog Devices], ADUM1100ARWZ Datasheet - Page 3

• Manufacturer Part Number: ADUM1100ARWZ
• Manufacturer: AD [Analog Devices]

IEC 61000-4-2 ESD Testing
A block diagram of the IEC 61000- 4-2 ESD test is shown
in Figure 3. In this test, ESD contact or air discharges are
applied at various points on a system chassis. This gives
rise to several mechanisms that can cause latch-up
problems for an iCoupler. These include injected current
via one of the iCoupler grounds as well as inductive
coupling from ESD currents in the system chassis or in
printed wiring board traces.
Injected ESD Current
The first possible mechanism for latch- up is one in
which excessive ESD current is injected into an iCoupler
ground. Figure 4 shows a situation where an iCoupler
is used as a floating output (the same mechanism can
be present in a floating input configuration). In this
REV. 0
AIR OR CONTACT
ESD ZAP TO 15kV
DISCHARGE
Figure 3. IEC 61000-4-2 ESDTest
SYSTEM CHASSIS
Z
ESD ZAP
CHASSIS
Figure 4. Injected ESD Current Mechanism and Recommended Solutions
CHASSIS/EARTH
SOURCE
GROUND
ESD
USE 50 RESISTOR TO
DECREASE I
I
INJECTED
50
CHASSIS
GROUND
INJECTED
ADDITION OF TRANSIENT
ABSORBER TO CLAMP
NOISE VOLTAGE AT GND
GND
V
DD1
D
IN
1
L3
–3–
C2
1
instance the chassis impedance, Z
to an injected current during an ESD discharge. This
current flows in the loop formed by L3, C2, L4, and
C
output cable to chassis ground. The larger the value of
C
internal noise voltage appearing across L4. If this voltage
forces GND
latch-up could occur.
The following measures are recommended to avoid
current injection difficulties:
• Minimize the chassis impedance to ground.
• Minimize C
• If possible place a 200  resistor in series with V
• Place a 50  resistor between chassis ground and
• Place a transient absorbing Zener diode from the
Inductive Coupling from ESD Current
One consideration is the possibility of inductive coupling
from ESD current present in the iCoupler printed wiring
board or system chassis. Inductive pickup on iCoupler
transformers from external magnetic fields is not a
problem in the vast majority of applications; however,
there have been rare instances in IEC 61000- 4-2 ESD
testing where this phenomenon has been noted.
Solutions to this problem are straightforward.
PIN
STRAY
STRAY
limit latch-up trigger current.
GND
connection to chassis ground. This clamps the noise
voltage to within the Zener voltage.
+V
C
NOISE
STRAY
, the larger the injected current and the consequent
. C
L4
1
. This reduces I
STRAY
–
200 RESISTOR TO LIMIT
LATCH-UP TRIGGER CURRENT
MINIMIZE SIZE OF C
COUPLING FROM OUTPUT
CABLE SHIELD TO CHASSIS
GROUND
2
beyond its absolute maximum rating, then
STRAY
V
D
GND
is the capacitance from the shield of an
DD2
OUT
, the cross-isolation barrier capacitance.
2
200
INJECTED
STRAY
V
LOGIC
,
and ultimately V
CHASSIS
, gives rise
AN-793
NOISE
DD2
.
to