Filters protect in clamshell handsets

Protection devices feature high attenuation, steep amplitude rolloff and low clamping voltage for high-performance colour LCD interfaces in 3G handsets.

The EClamp239xP is the latest addition to Semtech's EMIClamp protection portfolio.

The EClamp239xP is a series of inductor-capacitor (L-C) protection devices featuring greater attenuation, steeper amplitude rolloff and lower clamping voltage needed for high-performance colour LCD interfaces in GSM and CDMA-based 3G handsets.

The EClamp239xP series includes the four-line EClamp2394P, the six-line EClamp2396P and the eight-line EClamp2398P.

The EClamp239xP's five-pole L-C filter network has inductor values of 19nH and capacitor values of 12pF, enabling the devices to offer minimal attenuation in the passband and 30dB minimum attenuation from 800MHz to 2.7GHz, ideal for 3G-based mobile phones.

Each device in this series comprises TVS diodes for electrostatic discharge (ESD) protection and an L-C network for electromagnetic interference (EMI) and radio frequency interference (RFI) filtering.

Semtech's process technology combines spiral inductance on silicon, which provides performance advantages over RC devices and discrete solutions, such as higher attenuation and lower passband.

The EClamp239xP devices are available in the RoHS/WEEE-compliant Semtech leadless package (SLP), which offers the same small, low-profile design as "flip chip" alternatives, but with increased manufacturing durability.

The EClamp239xP packages are narrow (1.6mm) and low profile (0.58mm) with a variable length depending on the number of lines supported.

The flow-through design of the devices alleviates the need for signal routing for a faster and more convenient layout.

The large ground pad minimises parasitic inductance for improved ESD and filter characteristics.

The added functionality of 3G handsets, including camera, video, and Internet access, requires more parallel data lines, which boosts the amount of signal distorting EMI and RF.

Semtech's EClamp device series includes both L-C devices and resistor-capacitor (RC) devices thereby giving designers comprehensive options for ESD/EMI/RFI protection to better ensure a handset's integrity.

"These new EClamp devices offer the designer the attenuation and steep frequency roll off features needed to effectively filter out ESD and EMI at the high datarates of today's LCD interfaces, while also addressing the manufacturing durability needed for volume production", says Tom Dugan, Semtech Marketing Manager for Protection Products.

"The addition of a high-performance L-C filter to our EClamp family gives 3G handset designers another option, especially for clamshell designs where EMI issues can be greater due to separation of the processor and the camera/display".

The EClamp2394P is available immediately in production quantities and is priced at US $0.46 each in 1000-piece lots.

The EClamp2396P is available immediately in production quantities and is priced at $0.60 each in 1000-piece lots.

The EClamp2398P is available immediately in production quantities and is priced at $0.72 each in 1000-piece lots.

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