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Melexis introduces smallest 300-to-930-MHz transmitter chips on the market
November 3, 2003 - Ieper, Belgium -

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Melexis’ new 300 to 930MHz transmitter chip family, consisting of TH72005, TH72015 and TH72035, is the world’s first low-power and low-cost RF transmitter line packed in the very tiny MLP package. They enable designers to perfectly match their system requirements by each application’s frequency range, modulation scheme and output power requirement. This new automotive qualified line has been specifically designed for applications in the unlicensed Industrial-Scientific-Medical (ISM) and Short-Range-Devices (SRD) frequency bands.

The transmitters come in a space-saving 10 lead Micro Leadframe Package (MLP) with a footprint of only 3mm x 3mm. Compared to other solutions on the market, Melexis’ ICs do not require external components to set up the PLL loop filter or the VCO.

The TH720X5 ICs accept inputs from 1.9 to 5.5 V. Power consumption ranges from 3.5 mA to 14 mA depending on the frequency and power setting. In standby mode the current consumption is below 50 nA. The programmable RF transmit power range between -12 to 10dBm allows the designer to adapt to his RF power requirements.

These single-channel transmitter devices vary in frequency range to allow optimized performance over their bandwidth: TH72005 for 290 to 350 MHz, TH72015 for 380 to 450 MHz and TH72035 for 850 to 930 MHz. All three of them can be tuned in FSK, ASK or FM.

The TH720x5 transmitter ICs combine flexibility with high levels of circuit complexity. Compared to a SAW-based solution, the TH720x5 PLL-based transmitters offer substantially more frequency stability. At the same time they can be easily re-configured for another output frequency just by changing the crystal frequency. SAW transmitters, on the other hand, are limited because they are only available for certain operating frequencies.

Dr. Andreas Laute, Manager of Melexis’ Business Unit Wireless Communication, explains: “the primary goal in the development of all new transmitter, receiver, and transceiver products is to simplify design for the RF system engineers. We not only want to provide them with superior performance and design flexibility, but we want to do so across all popular non-licensed RF spectrums and other low-power broadcast formats.“

Typical applications for the TH720x5 transmitter IC family include security systems, home automation, garage door openers, wireless door bells, baby monitors. The extended operating temperature range of -40 to +125 °C makes the part ideally fit for automotive applications such as remote keyless entry (RKE), tire pressure monitoring systems (TPMS), car alarm systems, etc.

The new TH720x5 transmitter IC line completes the existing TH720xx family of transmitters which is housed in the widely used SOIC8 package. The parts can be used in virtually any FSK, ASK or FM system where the designer wants to eliminate wired hardware to form a completely wireless communications link. Melexis also offers corresponding receiver chips to complete the system.

In quantities of 100k, cost per unit for the TH72005, TH72015 or TH72035 is €0.56.