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RF transmitter zooms in on car access, TPMS apps

Posted: 26 May 2008 ?? ?Print Version ?Bookmark and Share

Keywords:RF? IC transmitter? TPMS car access?

Atmel Corp. has announced the availability of the new fully integrated fractional-N PLL RF transmitter IC ATA5749 for car access and TPMS applications. According to Atmel, the device is one of the very few automotive RF transmitter ICs that is fully programmable, thus enabling flexible system design and adaptation. In addition, the company touts the device's ultralow power consumptiona significant factor for TPMS applications. For both RKE and TPMS applications, a single crystal type and a single board design (with only minor modifications) can be used for the standard 315MHz and 433MHz frequency ranges.

The IC's single-ended antenna output power can be adjusted in the range of -0.5dBm to 12.5dBm via an SPI bus interface. In each mode, the lowest possible current consumption for a given output power can be selected. Furthermore, in extreme weather conditions, the battery lifetime is superior to comparable products.

In the event of a change in system specifications, where the output power needs to be adjusted, the current consumption of the ATA5749 can be optimized accordingly. The active current consumption is scalable by output power programming via SPI in 1-dB steps. This enables designers to fine tune system performance, in particular, RF link budget versus battery lifetime.

In addition to output power adjustments, the SPI bus interface also enables the programming of other key parameters such as output frequency, FSK signal deviation, and CLK output frequency.

The ATA5749 operates at a maximum data rate of 40Kbit/s in FSK and ASK mode using Manchester coding, and at an RF frequency in the range of 300-450MHz. The IC incorporates a robust crystal oscillator with fast start-up time of typically 200?s and a guaranteed parameter for negative resistance oscillation margin of 1,500?. This results in high reliability and helps avoid sleeping crystal issues. Only one 13.000000MHz crystal type is needed for the standard frequency ranges 314.1-329.5MHz and 424.5-439.9MHz, resulting in nearly identical hardware board design for the regional RF modules, lower inventory costs, and reduced part number proliferation, says Atmel.

Samples of the ATA5749 RF transmitter IC are available now in small-outline TSSOP10 packages. Pricing starts at $1.25 for 10,000-piece quantities. A demonstration board for development support is also available.

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