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Low-capacitance protection devices support HDMI 1.3

Posted: 06 Nov 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Semtech? RClamp0524P? RClamp0522P? protection devices? HDMI 1.3?

Low-capacitance protection devices from Semtech

Semtech Corp. has announced the RClamp0524P and RClamp0522P, two new 5V protection devices that the company claims 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 color depth and audio output. HDMI 1.3 doubles the data rate of HDMI signals to 3.4Gbps per differential pair.

0.3pF capacitance
Protecting 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, Semtech said, allowing either to be used on circuits operating at speeds greater than 3GHz without signal attenuation. The ultralow capacitance means 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 IEC 61000-4-2 standard for ESD protection (115kV for air, 18kV 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 ultrathin 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 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.

High-speed interfaces
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-by-1-by-0.58mm. The small size of the RClamp0522P, which comes in a 6-pin SLP1610P4 package measuring 1.6-by-1-by-0.58mm, is designed for portable applications with high-speed displays such as cellphones and PDAs. These 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. RClamp0524P is priced at 35 cents each in 1,000-piece quantities. RClamp0522P is priced at 35 cents each in 1,000-piece quantities. Semtech offers comprehensive design assistance, including field- and factory-based support.

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