SLVU2.8 Datasheet, PDF (5/10 Pages) Semtech Corporation – Low Voltage EPD TVS Diode For ESD and Latch-Up Protection

SLVU2.8
PROTECTION PRODUCTS
Applications Information
Device Connection Options
SLVU2.8 Circuit Diagram
Electronic equipment is susceptible to transient distur-
bances from a variety of sources including: ESD to an
open connector or interface, direct or nearby lightning
strikes to cables and wires, and charged cables “hot
plugged” into I/O ports. The SLVU2.8 is designed to
protect sensitive components from damage and latch-
up which may result from such transient events. The
SLVU2.8 can be configured to protect either one
unidirectional line or two (one line pair) high-speed data
lines. The options for connecting the devices are as
follows:
1
3
2
Protection of one unidirectional line
1 . Protection of one unidirectional I/O line: Protec-
tion of one data line is achieved by connecting pin
3 to the protected line, and pins 1 and 2 to ground.
This connection option will allow the device to
operate on lines with positive polarity signal transi-
tions (during normal operation). In this configura-
tion, the device adds a maximum loading capaci-
tance of 100pF. During positive duration tran-
sients, the internal TVS diode will be reversed
biased and will act in the avalanche mode, con-
ducting the transient current from pin 3 to 1. The
transient will be clamped at or below the rated
clamping voltage of the device. For negative
duration transients, the internal steering diode is
forward biased, conducting the transient current
from pin 2 to 3. The transient is clamped below
the rated forward voltage drop of the diode.
Low capacitance protection of one high-speed line
pair
2. Low capacitance protection of one differential
line pair: Protection of a high-speed differential line
pair is achieved by connecting two devices in anti-
parallel. Pin 1 of the first device is connected to
line 1 and pin 2 is connected to line 2. Pin 2 of the
second device is connected to line 1 and pin 1 is
connected to line 2 as shown. Pin 3 must be left
open on both devices. During negative duration
transients, the first device will conduct from pin 2
to 1. The steering diode conducts in the forward
direction while the TVS will avalanche and conduct
in the reverse direction. During positive transients,
the second device will conduct in the same man-
ner. In this configuration, the total loading capaci-
tance is the sum of the capacitance (between pins
1 and 2) of each device (typically <10pF) making
this configuration suitable for high-speed interfaces
such as 10/100 Ethernet (See application note
SI98-02).
EPD TVS Characteristics
The SLVU2.8 is constructed using Semtech’s propri-
etary EPD technology. The structure of the EPD TVS is
vastly different from the traditional pn-junction devices.
At voltages below 5V, high leakage current and junction
capacitance render conventional avalanche technology
impractical for most applications. However, by utilizing
the EPD technology, the SLVU2.8 can effectively
operate at 2.8V 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. The EPD mecha-
nism is achieved by engineering the center region of
the device such that the reverse biased junction does
© 2008 Semtech Corp.
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