4 2005 Semtech Corp.
www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
LCDA12C-1 and LCDA15C-1
Applications Information
Device Connection for Metallic Protection of High-
Speed Data Lines
The LCDAxxC-1 is designed to protect high-speed data
lines from transient over-voltages which result from
lightning and ESD. The device is designed to protect
one line in common mode (Line-to-Ground) or one line
pair in metallic (Line-to-Line) mode. For metallic mode
protection, the input of line 1 is connected at pin 1 and
the output is connected at pin 4. Likewise, the input
of line 2 is connected at pin 2 and the output is con-
nected at pin 3. For common mode protection, ground
either pins 1 and 4 or pins 2 and 3. The ground
connection should be made directly to the ground
plane for best results.
ADSL Protection
A typical ADSL protection circuit is shown in Figure
3. The LCDA12C-1 (or LCDA15C-1 for 15 volt drivers)
is connected from each line to ground on the IC side of
the line. They provide lightning and ESD protection for
the sensitive line driver IC.
Matte Tin Lead Finish
Matte tin has become the industry standard lead-free
replacement for SnPb lead finishes. A matte tin finish
is composed of 100% tin solder with large grains.
Since the solder volume on the leads is small com-
pared to the solder paste volume that is placed on the
land pattern of the PCB, the reflow profile will be
Figure 3 - ADSL Protection Circuit
1
2
3
4
Line
In
Line
In
Line
Out
Line
Out
Figure 1 - Connection for Differential Protection
(Line-to-Line)
1
2
3
4
Line
In
Line
Out
Figure 2 - Connection for Common Mode
Protection (Line-to-Ground)
determined by the requirements of the solder paste.
Therefore, these devices are compatible with both
lead-free and SnPb assembly techniques. In addition,
unlike other lead-free compositions, matte tin does not
have any added alloys that can cause degradation of
the solder joint.
