Transceiver ICs for ISM-band applications

Melexis introduces two new ASK/FSK/FM RF transceiver ICs with an exceptional tuning range covering 27 to 937MHz, suitable for short range operations

The TH7122 and TH71221 are designed for virtually every application in the unlicensed Industrial-Scientific-Medical (ISM) or Short-Range-Devices (SRD) frequency bands.

Target applications are bidirectional tyre pressure monitoring systems (TPMS), wireless networking solutions, RF tags, alarm systems and security monitoring, home automation, garage door openers, automatic meter reading, remote sensors, etc.

With a frequency range of 27 to 930MHz the TH7122 and TH71221 have the widest operating range currently available on the market.

The chips have been optimized for half-duplex FSK transmit and receive systems and can also be used for ASK receiver applications as well as ASK transmit applications with low output power requirements.

The receiver has internal ASK/FSK switching.

An analog FM detector can be used for FSK or audio.

The new RF transceiver ICs are an evolution of the former Melexis transceiver TH7120.

In order to allow users of the existing TH7120 transceiver to upgrade easily to the TH7122, the package pin-out of the 32-lead LQFP has been modified only on two pins.

Customers with tight board size requirements can use the new transceiver TH71221 in a space-saving 32-lead Micro Leadframe Package (MLP) with a footprint of only 5mm x 5mm.

The transceivers can be set in different frequency and power modes.

Both a stand-alone fixed-frequency mode and an externally programmable, frequency-agile mode are available.

Transmit, receive, standby and two idle modes allow for power-efficient polling regimes.

The fully synthesized LC tuned VCO with an on-chip varactor has both programmable reference and feedback dividers which allow a large range of frequency steps and reference frequencies.

This allows the transceiver to be used with its own crystal or an external reference from 1 to 16MHz from a microprocessor or TCXO.

An on-chip AFC has been integrated to improve the receiver frequency acceptance range.

The TH7122 and TH71221 transceiver ICs combine flexibility with high levels of circuit integration.

The user has the choice to select an external ceramic IF filter to optimize the performance for the application.

Whether frequency agility is key or a simple and low-cost fixed-frequency application is needed the TH7122x transceivers can be used either way.

According to Dr Andreas Laute, Manager of Melexis' Business Unit Wireless Communication, the primary goal in the development of all new transceiver, transmitter and receiver 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 as well as other low-power communications formats." In quantities of 100k, cost per unit for the TH7122 is Euro1.44.

This part is now available in volumes.

The MLP version TH71221 is now available in pre-production volumes and will be ready for volume production in March 2005.

Its 100k unit price is Euro1.41.

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