AN2321 Freescale Semiconductor / Motorola, AN2321 Datasheet - Page 10

• Manufacturer Part Number: AN2321
• Description: Designing for Board Level Electromagnetic Compatibility
• Manufacturer: Freescale Semiconductor / Motorola

AN2321/D
Diodes
10
Rectifier diode
Schottky diode
Zener diode
Light emitting diode
Transient voltage
Varistor diode
(VDR: voltage
(MOV: metal oxide
(LED)
suppressor diode
(TVS)
dependent resistor)
varistor)
Large current; slow response; low
Low forward voltage drop; high
Operation in reverse mode; quick
Forward conduction mode; no
Similar to zener diode but in an
Metal coated ceramic pills (each
cost.
current density; fast reverse
transient time.
reverse voltage transients;
clamp positive transients only;
tight clamp voltage
specifications (5.1V ± 2%).
EMC impact by itself.
avalanche mode; wide clamp
voltage tolerance (e.g. 5V
means clamp between 6V to
12V); clamp positive and
negative voltage transients.
pill works as schottky diode with
high potential barrier; mains line
protection; fastest response to
transients.
In
filtering by its leakage inductance and differential mode filtering by its primary
inductance. L1, C
filter out noise between the supply lines. L1, C
mode filtering network which reduces noise from ground loops and earth offset.
For a 50 Ω terminating impedance, the EMI filter typically can fall-off at about
50dB/decade in differential mode and 40dB/decade in common mode.
The diode is the simplest form of semiconductor devices. Based on their
individual characteristics, some diodes can help to resolve and protect from
EMI related problems.
Designing for Board Level Electromagnetic Compatibility
Figure
Freescale Semiconductor, Inc.
For More Information On This Product,
Characteristic
7, L1 is the common mode choke, which provide both common mode
Table 2. Diode Characteristics
Go to: www.freescale.com
X1
, and C
Table 2
X2
forms the differential filtering network which is to
Nil
Fast transient signals and
ESD protection; over voltage
Nil
High voltage transient from
First line ESD protection; high
summarizes the type of diodes.
spike protection.
protection; low capacitance
high data rate signalling
protection.
ESD lighting – induced
transient main spikes.
voltage and high transient
protection.
EMC Application
Y1
, and C
Y2
forms the common
Power supply
Switched mode
Radiated
Alternative to
units.
power supplies.
emission when
LED is mounted
on a panel at a
distance away
from the PCB.
zener or TVS.
Comments
MOTOROLA
—
—