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UHF ASK/FSK receiver ICs lay claim to industry’s smallest footprints

Heilbronn, Germany—IC maker Atmel Corp . is publishing preliminary datasheets, and is sampling, two single-chip BiCMOS RF receiver ICs for RKE (remote keyless entry) and TPMS (tire pressure monitoring system) applications. Sized at 5 x 5-mm (200-mils square), Atmel claims they're the industry's smallest footprint devices.

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

Outboard Microcontrollers

The ATA5745 operates in the 433-MHz to 435-MHz band. The ATA5746 covers the 313-MHz to 315-MHz 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 52-ms.

Both ICs also integrate IF filters, low-phase-noise VCO s (voltage-controlled oscillators), PLL s (phase-locked loops), and loop filters. As totally integrated RF circuits, they achieve typical image rejection specs of 30-dB.

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 do 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 1-kbit/s to 20-kbit/s 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 1-ms.

Antenna Matching

Active current demand is specified at about 6.5-mA. That's based on a single-ended RF input for adaptation of 1/4-wave or printed loop antennas.

Samples are available now in QFN24 packages.

Pricing starts at about $1.40 eachh, in quantities of 10,000.

Atmel also offers evaluation boards (dubbed the ATA5745-EK and ATA5746-EK . These are priced at less than $100 each.

Click here for a preliminary datasheet. It's in Adobe Acrobat .PDF format.

For more details contact Atmel Corp., 2325 Orchard Parkway, San Jose, Calif. 95131. Phone: 408-441-0311

Atmel , 408- 441-0311, www.atmel.com

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