ST AN3357 APPLICATION NOTE
AN3357
Application note
HSP061-8M16 high speed line protection on HDMI 1.4 link
Introduction
This Application note presents the HSP061-8M16 and its capability to protect HDMI 1.3 and
HDMI 1.4 TMDS lines.
The HDMI interface is provided for transmitting digital television audiovisual signals from
DVD players, set-top- boxes and other source to television sets and other video displays.
HSP061-8M16 has been developed to be compliant with:
■ HDMI version 1.4 standard knowing the key point is the capability to transfer data with a
maximum rate of 3.4 Gbps per channel without distortion. This leads the HSP061-8M16
to have a large bandwidth, to pass fast voltage slope and to keep the 100 Ω line
impedance, HSP061-8M16 is used on the TMDS line.
■ IEC 61000-4-2 level 4 (15 kV contact discharge)
April 2011 Doc ID 018580 Rev 1 1/10
www.st.com
Location for HSP061-8M16 AN3357
1 Location for HSP061-8M16
Many PCB parasitic elements may degrade the overall ESD performance of a system. The
recommendations below are aimed at optimizing ESD protection device placement and the
PCB layout to reach the best ESD performance possible.
The layout shown in Figure 1 may induce parasitic inductances responsible for artificial
overvoltages directly applied on the IC to be protected.
Figure 1. Non-optimized location for
HSP061-8M16
16
1
16
2
15
3
14
4
Via to GND
13
G
N
5
12
D
6
11
10
7
8
=
9
Via to
GND
IC to
protect
Figure 2. Significant overvoltages due
to non-optimal location of
HSP061-8M16
V
di
L
dt
ESD surge is 15 kV with 1 ns
rise time, this leads to 71 A/ ns
GND layer
IC to
protect
V
IC
Via to
GND
A very simple calculation shows that for a 15 kV ESD contact surge according to
IEC61000-4-2, the overvoltage due to parasitic inductances may be really significant, as
shown in Figure 2. This test is done with a contact discharge as the air discharge waveform
is not defined in the IEC 61000-4-2 specification. Assuming that each inductance value is 5
nH (corresponds to metal track 5 mm long):
di
= 71 A/ns
dt
then the overvoltage seen by the IC is:
V = V +
IC
V = V + 355 V
IC
di
L·
dt
This parasitic inductance must be reduced as much as possible by shortening the ground
path return to the GND via.
To avoid ESD propagation on the PCB, the ESD protection must be placed as close as
possible to the ESD source with the layout given in the datasheet.
The layout given in the datasheet reduces parasitic inductance. It is important to connect the
connector on one side of the HSP and the transceiver on the other side. The GND via on
both sides must be used.
As ESD stress can be propagated on both sides of the cable, a protection device on each
end of the cable is required.
2/10 Doc ID 018580 Rev 1
AN3357 Location for HSP061-8M16
Figure 3. Protection location on HDMI equipment
Protection
Tx
Board
Receptacle
(connector)
Source device (i.e., DVD)
Wire
Plug
Cable assembly
Protection
Rx
Board
Receptacle
(connector)
Sink device (Display)
Doc ID 018580 Rev 1 3/10
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