Protection devices combine for HDMI interfaces

ESD and overcurrent protection reference layout meets or exceeds the HDMI 1.3 specifications for operation at 3.4Gbit/s for impedance, data eye and far end crosstalk.

Tyco Electronics has devised a reference layout for ESD and overcurrent protection for HDMI 1.3 interfaces.

The reference layout uses low-capacitance (0.25pF signal to ground) PESD protection devices, and space-effective component placement and routing to help protect against ESD events and optimise board space.

The reference layout also includes optional overcurrent protection on the +5V rail, using the PolySwitch nanoSMD device.

The newest HDMI 1.3 standard doubles the previous HDMI datarate to 3.4Gbit/s per differential signal pair.

With such high data transmission rates, low capacitance and good board design are crucial to provide adequate signal integrity.

Tyco Electronics' new ESD and overcurrent protection reference layout for HDMI 1.3 was developed in conjunction with Efficere, a leader in high-speed interface design and test, and meets or exceeds the HDMI 1.3 specifications for operation at 3.4Gbit/s for impedance (TDR), data eye and far end crosstalk.

"Achieving the optimum signal integrity and crosstalk performance with HDMI layouts is complicated and adding ESD protection amplifies the design challenge", says Efficere Technologies Vice President of Sales, Joe O'Brien.

"Efficere has worked with Tyco Electronics to develop a layout with ESD protection that exceeds HDMI 1.3 requirements and can help reduce electronic equipment manufacturers' time to market".

The bidirectional PESD0603 or PESD0402 devices are configured in a very small space behind the HDMI connector and help designers meet the IEC61000-4-2 standard for ESD protection (+/-15kV for air, +/-8kV for contact).

The PESD devices are offered in EIA standard 0603 and 0402 sizes and can be used in various end applications, including DisplayPort, WiMAX and cellular basestations, eSATA and other high-speed data and analogue interfaces.

In HDMI source devices, such as DVD players, set-top boxes, computers and other HD sources, the specification requires that the transmitter interface's voltage rail include overcurrent protection to prevent short circuit or abnormally high current from damaging the source device.

Tyco Electronics' protection layout includes optional overcurrent protection on the +5V rail, using the popular PolySwitch nanoSMD circuit protection device.

The PESD0603, PESD0402 and PolySwitch nanoSMD devices are available today in volume and are compatible with standard surface-mount and reflow installation procedures.

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