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PROTECTION PRODUCTS
RClamp2504P & RClamp3304P
Device Connection for Protection of Four High-Speed
Data Lines
These devices are designed to protect low voltage data
lines operating at 2.5 volts or 3.3 volts. When the
voltage on the protected line exceeds the TVS working
voltage, the steering diodes are forward biased,
conducting the transient current away from the
sensitive circuitry, through the internal TVS to ground.
Data lines are connected at pins 1, 2, 5 and 6. The
center pin should be connected directly to a ground
plane. The path length is kept as short as possible to
minimize parasitic inductance. For best results,
multiple micro-vias connected to ground are
recommended. Pins 3 and 4 are not connected.
Note that pin 3 is connected internally to the cathode
of the low voltage TVS. It is not recommended that
this pins be directly connected to a DC source greater
than the snap-back votlage (V
SB
) as the device can
latch on as described below.
EPD TVS Characteristics
These devices are constructed using Semtech’s
proprietary EPD technology. By utilizing the EPD tech-
nology, the device can effectively operate at 3.3V while
maintaining excellent electrical characteristics.
The EPD TVS employs a complex nppn structure in
contrast to the pn structure normally found in tradi-
tional silicon-avalanche TVS diodes. Since the EPD
TVS devices use a 4-layer structure, they exhibit a
slightly different IV characteristic curve when compared
to conventional devices. During normal operation, the
device represents a high-impedance to the circuit up to
the device working voltage (V
RWM
). During an ESD
event, the device will begin to conduct and will enter a
low impedance state when the punch through voltage
(V
PT
) is exceeded. Unlike a conventional device, the low
voltage TVS will exhibit a slight negative resistance
characteristic as it conducts current. This characteris-
tic aids in lowering the clamping voltage of the device,
but must be considered in applications where DC
voltages are present.
When the TVS is conducting current, it will exhibit a
slight “snap-back” or negative resistance
characteristics due to its structure. This point is
defined on the curve by the snap-back voltage (V
SB
)
Applications Information
Protection of Four Data Lines
1
Gnd
Figure 1Figure 1
Figure 1Figure 1
Figure 1
. Pin Conf. Pin Conf
. Pin Conf. Pin Conf
. Pin Conf
iguration (Tiguration (T
iguration (Tiguration (T
iguration (T
op Side Vieop Side Vie
op Side Vieop Side Vie
op Side Vie
w)w)
w)w)
w)
1
Gnd
2
3
6
5
4
niPnoitacifitnedI
6,5,2,1seniLtuptuO/tupnI
4detcennoCtoN
3
V3.3roV5.2
)ylppusCDaotnipsihttcennoctonoD(
Vnahtre
taerg
BS
)
baTretneCdnuorG
and snap-back current (I
SB
). To return to a non-
conducting state, the current through the device must
fall below the I
SB
(approximately <50mA) and the
voltage must fall below the V
SB
(normally 2.8 volts for a
3.3V device). If a 3.3V TVS is connected to 3.3V DC
source, it will never fall below the snap-back voltage of
2.8V and will therefore stay in a conducting state.
