Protection devices cut capacitance

Two new 5V protection devices are the first solid-state devices to reach 0.3pF in capacitance to meet the needs of High Definition Multimedia Interface 1.3 and other high-speed data lines.

Semtech Corp has announced the RClamp0524P and RClamp0522P, two new 5V protection devices that are the first solid-state devices to reach 0.3pF in capacitance to meet the needs of High Definition Multimedia Interface (HDMI) 1.3 and other high-speed data lines.

HDMI has been a dramatic success with more than 60 million HDMI-equipped devices shipped in 2006.

In June 2006, the new HDMI 1.3 standard was introduced for improved colour depth and audio output.

HDMI 1.3 doubles the datarate of HDMI signals to 3.4Gbit/s per differential pair.

Protecting the data lines at those speeds is a challenge because introducing any significant capacitance on the line will degrade signal integrity.

The four-line RClamp0524P and two-line RClamp0522P are TVS arrays with a capacitance of 0.3pF between I/O pins, allowing either to be used on circuits operating at speeds greater than 3GHz without signal attenuation.

The ultralow capacitance means that common-mode chokes are not required for impedance compensation in HDMI designs.

Aggressive ESD protection is essential on HDMI systems because the increased usage of video cameras, game consoles, DVD players and other appliances increases the risk of a cable discharge event (CDE), which is a type of ESD.

The new RClamp devices meet the stringent IEC61000-4-2 standard for ESD protection (+/-15kV for air, +/-8kV for contact).

The devices also meet IEC standards for electrical fast transients (EFT) and for lightning strikes.

Both devices come in special SLP-style packages with an ultra thin design that reduces trace discontinuities.

The package is leadless to reduce stubs that can impact signal quality, and has a flow- through design to avoid trace routing issues that can impact signal integrity.

The devices also feature a 0.5mm lead pitch so that the differential traces can be tightly coupled for good common-mode noise rejection.

These features, combined with 0.3pF capacitance, mean the devices can be used on two-, four- or six-layer boards without added trace compensation, eliminating "guesswork" in the layout.

Silicon Image, a leader in interconnect semiconductors for the global PC/display, consumer electronics and storage markets, is evaluating the new RClamp0524P for its HDMI 1.3 reference designs.

"Silicon Image prefers to use TVS devices in our reference designs".

"While technologies such as polymers, varistors and BAV99s may allow for the successful completion of the HDMI CTS, only a low capacitance and low clamping voltage TVS device provides adequate safeguard against latch-up and EOS/ESD threats", said Rob Frizzell, Director of HDMI Product Marketing at Silicon Image.

"Semtech TVS protection devices are used on Silicon Image HDMI reference designs due to their excellent clamping and signal integrity characteristics".

"The whole purpose of HDMI 1.3 is to give consumers a better viewing and listening experience, and the RClamp0524P chips are the first TVS devices that give these systems the level of protection they need without impacting signal integrity", said Tom Dugan, Semtech's Director of Protection Products.

"The capacitance of these devices is half of the industry norm for TVS arrays, and is a significant achievement for the Semtech team".

"I would go so far as to say that this has the potential to be the protection industry's biggest innovation this year".

The RClamp0524P is designed primarily for HDMI applications, where only two devices are needed to protect all of the high-speed data lines coming from an HDMI connector.

It is available in a 10-pin SLP2510P8 package measuring 2.5 x 1.0 x 0.58mm.

The small sise of the RClamp0522P, which comes in a 6-pin SLP1610P4 package measuring 1.6 x 1.0 x 0.58mm, is designed for portable applications with high-speed displays such as cellphones and personal digital assistants.

The devices can also be used to protect MDDI, DisplayPort, UDI, InfiniBand and other high-speed data interfaces.

Both new RClamp devices are available immediately in production quantities.

The ordering code for the RClamp0524P is RClamp0524P.TCT, and the device is priced at US $0.35 each in 1000-piece quantities.

The ordering code for the RClamp0522P is RClamp0522P.TCT, and it is priced at $0.35 each in 1000-piece quantities.

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