ECLAMP2374K.TCT Semtech, ECLAMP2374K.TCT Datasheet - Page 5

• Manufacturer Part Number: ECLAMP2374K.TCT
• Description: EClamp ESD/EMI Protection For Color LCD Interfaces, 4 Lines
• Manufacturer: Semtech

Figure 3 shows the recommended device layout. The
ground pad vias have a diameter of 0.008 inches
(0.20 mm) while the two external vias have a diameter
of 0.010 inches (0.250mm). The internal vias are
spaced approximately evenly from the center of the
pad. The designer may choose to use more vias with a
smaller diameter (such as 0.005 inches or 0.125mm)
since changing the diameter of the via will result in
little change in inductance (i.e. the log function in
Equation 2 in highly insensitive to parameter d) .
Figure 4 shows a typical insertion loss (S21) plot for
the device using Semtech’s filter evaluation board with
50 Ohm traces and the recommended via configura-
tion. Figure 5 shows a typical insertion loss (S21) plot
using a similar board without the internal ground pad
vias. The result is a more inductive ground loop. Note
the “hump” at a frequency of 2.5GHz. This is the
resonant frequency of the higher ground loop induc-
tance.
PROTECTION PRODUCTS
© 2008 Semtech Corp.
Applications Information
Figure 3 - Recommended Layout Using Ground Vias
5
Figure 4 - Filter Characteristics Using Recommended
Figure 5 - Filter Characteristics Using Layout without
-12 dB
-18 dB
-24 dB
-30 dB
-36 dB
-12 dB
-18 dB
-24 dB
-30 dB
-36 dB
-42 dB
-48 dB
-6 dB
-6 dB
0 dB
0 dB
START . 030 MHz
START . 030 MHz
CH1 S21
CH1 S21
Layout with Internal Vias
LOG
LOG
Internal Ground Vias
MHz
MHz
1
1
6 dB / REF 0 dB
6 dB / REF 0 dB
MHz
MHz
10
10
EClamp2374K
MHz
MHz
100
100
STOP 000 . 000 000 MHz
STOP 000 . 000 000 MHz
1
1
PRELIMINARY
GHz
GHz
3
3
2
2
1
1
www.semtech.com
3
3
GHz
GHz
4
4
3
3
1: -9.1473 dB
2: -19.559 dB
3: -30.645 dB
4: -34.705 dB
1: -8.9400 dB
2: -20.032 dB
3: -23.761 dB
4: -16.085 dB
297.671 MHz
288.002 MHz
900 MHz
1.8 GHz
2.5 GHz
900 MHz
1.8 GHz
2.5 GHz