ESD-CDE Circuit Protection For High Definition Multimedia Interface

Application Brief
SEMTECH
PROTECTION
PRODUCTS
ESD/CDE Protection
For High Definition Multimedia Interface (HDMI)
Breakthrough protection device for HDMI 1.4 with ultra low cap. of 0.25pF
High Definition Multimedia Interface (HDMI) is an
uncompressed, all-digital audio/video interface that
provides a high-speed link between audio/video
source devices, such as DVD players, and sink devices,
such as HDTV. In order to receive HDMI certification,
both sink and source devices need to comply with
respective test requirements set forth by the HDMI
Compliance Test Specification (CTS). HDMI 1.4 is the
current specification, which runs at a maximum rate of
3.4 Gbps per channel and is capable of transmitting
uncompressed signals up to 10.2 Gbps under typical
HDMI connection (3 TMDS channels).
With the increase in data speed, signal integrity
maintenance is crucial in order to meet HDMI eye
pattern and TDR requirements. This is not a trivial task
since the differential impedance can be easily
affected by the introduction of even a small amount of
capacitance or inductance. In addition, the externally
accessible HDMI ports are becoming increasingly
more susceptible to transient threats. The threats
can come from any charged entity; for example, from
either a user’s direct touch or from hot plugging a
charged cable. The internal on-chip ESD structures
do not provide sufficient protection needed to keep
the sensitive HDMI chip from becoming damaged.
To protect against the over-voltage stress induced by
users and ESD testing, external protection is required.
With this added concern, HDMI designers need to
meet the ESD immunity requirement of IEC 61000-4-2
while maintaining signal integrity and impedance
requirements per the HDMI CTS.
Requirements
• Pass Compliance Test Specification (CTS) on sink
and source sides: 100 +/- 15% trace impedance
• Pass eye pattern test using HDMI eye mask
Applications and Features
• Ultra-low capacitance: 0.25pF typical (line-to-line)
• Industry’s lowest clamping voltage
• Small package solution, including flow through
leadless package (SLP) to maintain signal integrity
• Solid-state silicon-avalanche technology does not
degrade after repeated strikes
• RoHS/WEEE Compliant
• Meets industry immunity standard:
IEC 61000-4-2 (ESD) +/-18kV (air), +/-12kV (contact)
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RClamp® 0584J for HDMI 1.4
With a maximum differential capacitance value of 0.4pF,
Semtech’s RClamp0584J can be used directly on 2
pairs of 100 Ohm differential impedance signal lines
regardless of the board type, number of layers, thickness,
or board material. To further facilitate the high-speed
design, RClamp0584J is housed in a small leadless
package with 0.5mm pitch, flow-through layout. The
package design helps to reduce discontinuities and
increase common noise rejection through tight-pitch
coupling. Figure 1 (see below) shows an example of
high-speed differential trace routing with Semtech’s
RClamp0584J.
In addition to streamlining high-speed signal line design
and maintaining the impedance requirement, RClamp0584J
is designed specifically to provide ESD protection to
Level 4, IEC 61000-4-2 ESD standard (±12kV contact
ESD and ±18kV air ESD) and, at the same time, to
provide superior clamping voltage performance. The
RClamp0584J’s low clamping voltage reduces the
over-voltage stress on the HDMI chip, which increases
the overall HDMI system’s reliability.
Test Results and Recommendations
The low capacitance, clamping voltage, and operating
voltage of the Semtech’s RClamp0584J, coupled with
its innovative package design, make it a superior
protection device for HDMI applications. Semtech has
produced 4-layer HDMI evaluation board, for customers
to evaluate the RClamp0584J’s TDR and eye pattern
performance. Figure 2 shows the TDR result on HDMI
evaluation board. The result shows that the TDR has
met, and is well within, the HDMI CTS requirement
(100 Ohm ±15% for differential impedance).
1
8
2
7
GND
GND
3
6
4
5
1
8
2
7
GND
GND
3
6
4
5
Figure 1: Flow-through layout of Semtech’s RClamp0584J for HDMI Applications
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RClamp® 0584J for HDMI 1.4
X-axis
1.79
nsec
Y-axis
98.3
ohm
Figure 3: RClamp0584J HDMI Eye Pattern Result
Figure 2: RClamp0584J 4-Layer HDMI TDR Result
Conclusion
Designers of HDMI systems are faced with the difficult
challenge of providing reliable ESD protection while
meeting the signal integrity requirement per HDMI CTS.
Proper selection of added external protection devices is
imperative. The chosen protection device must exhibit very
low capacitance while keeping the ESD clamping voltage
at a minimum to maintain the quality and reliability of
the protected IC. This will ensure that the HDMI chip
will not experience catastrophic or latent failure during
a transient threat.With an ultra-low capacitance value
and superior ESD protection capability, Semtech’s
RClamp0584J will ensure the compliance of an HDMI
application to both HDMI 1.4 CTS and ESD requirements
without the need for any further board or device
compensation.
Electrical Characteristics (T=25°)
Parameter
Symbol
Conditions
Minimum
Typical
Maximum
Units
Reverse Stand-Off Voltage
VRWM
Any I/O pin to ground
5
V
Reverse Breakdown Voltage
VBR
It=1mA
Any I/O pin to ground
Reverse Leakage Current
IR
VRWM=5V, T=25°C
Any I/O pin to ground
0.1
µA
Clamping Voltage
Vc
Ipp=1A, tp=8/20µs
Any I/O pin to ground
12
V
Junction Capacitance
Cj
VR=OV, f=1MHZ
Between I/O pins
0.4
pF
Junction Capacitance
Cj
VR=OV, f=1MHz
Any I/O pin to ground
0.6
pF
6.5
V
0.25
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RClamp® 0584J for HDMI 1.4
Application Brief
Outline Drawing – SLP2710P8
Land Pattern – SLP2710P8
Semtech and the Semtech logo are registered marks of Semtech Corporation. All other trademarks and trade names mentioned may be marks and names of their respective companies. Semtech reserves the
right to make changes to, or discontinue any products described in this document without further notice. Semtech makes no warranty, representation or guarantee, express or implied, regarding the suitability of its
products for any particular purpose. ©2011 Semtech Corporation. All rights reserved. HDMI-APPB-1111
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