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Atmel RF receivers tout 'smallest' footprint

Posted: 27 Jul 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Atmel? ATA5745? ATA5746? RF receiver? XX?

IC maker Atmel Corp. is publishing preliminary datasheets and is sampling two single-chip BiCMOS RF receiver ICs for remote keyless entry (RKE) and tire pressure monitoring system (TPMS) applications. Sized at 5-by-5mm, Atmel claims they're the industry's smallest footprint devices.

Offering an optimized trade-off between bandwidth and selectivity, Atmel's ATA5745 and ATA5746 alternating shift keyed/frequency shift keyed (ASK/FSK) receiver ICs extend the company's existing portfolio of automotive RF devices.

Outboard microcontrollers
The ATA5745 operates in the 433MHz to 435MHz band. The ATA5746 covers the 313MHz to 315MHz band. The ATA5745 and ATA5746 operate in combination with separate microcontrollers for bit check and polling modes.

These devices also support header and blanking periods in ASK mode, as required by typical protocols used in the USA, with a telegram pause length up to 52ms.

Both ICs also integrate IF filters, low-phase-noise voltage-controlled oscillators, PLLs and loop filters. As totally integrated RF circuits, they achieve typical image rejection specs of 30dB.

On-chip filters
With integrated filters, these ICs let you develop TPMS and RKE circuits ranging from sophisticated ones to very low cost ones. Atmel claims competing ICs can't address low-cost systems due to their smaller bandwidth.

These receiver ICs also demand few external components. They also need no external filters. Eight passive components, a crystal and an antenna are typically all that's needed to create a receiver board. Thanks to the IC's large oscillation margin, you can also choose very low-cost crystals.

Unified RKE/TPMS applications
Due to their fast switching capability between TPMS and RKE signals, ATA5745 and ATA5746 devices can also be used in unified RKE/TPMS automotive application environments with different system definitions. This can eliminate the need for two separate RKE and TPMS chips.

The ICs' ability to change the modulation type between ASK and FSK, and between data rates without component changes, is important when receiving different RKE/TPMS modulation schemes and data rates.

These receiver devices can be operated in 1Kbps to 20Kbps Manchester-encoded FSK mode with four different baud rate ranges. That's selectable through a microcontroller without any hardware modification. Typical switching between modulation types and data rates occurs in less than 1ms.

Samples of the , ATA5745 and ATA5746 devices are available in QFN24 packages, and pricing starts at $1.40 each in quantities of 10,000. Atmel also offers evaluation boards (ATA5745-EK and ATA5746-EK) priced at less than $100 each.

- Alex Mendelsohn

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