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Automotive tire-pressure RFICs pack integral microcontrollers

San Jose, Calif.—Based on Atmel Corp .'s popular 8-bit flash-equipped AVR microcontroller architecture, highly-integrated low-power ATA6285 and ATA6286 microcontroller-transmitter ICs include sensor interfaces for TPMS (tire pressure monitoring) sensors.

Atmel's in-system-programmable devices include all necessary building blocks to support the measurement and calibration of simple capacitive pressure and motion sensors, plus a complete RF transmission function.

The ATA6285 operates at 315-MHz, and the ATA6286 counterpart is for 433-MHz operation. Both devices are suited for ASK (amplitude-shift keyed) and FSK (frequency-shift keyed) transmissions at typical data rates of 10-kbaud with Manchester encoding.

These ICs can be operated at 2-V to 3.6-V, and will work from a single lithium-ion cell source. What's more, they'll operate from -40°C to +125°C, and live quite well up to +150°. That's just what's needed in hostile automotive applications.

Non-Calibrated Sensor Support

These ICs also let you choose simple low-cost non-calibrated sensors. Cheap capacitive sensors can be calibrated readily by firmware running on the IC's integrated AVR microcontrollers. This feature also suits these ICs for sensor manufacturers developing their own integrated sensor modules.

These latest ingle-package devices also borrow Atmel's existing ATA5756 and ATA5757 RF transmitter chip circuitry. But, the ATA6285 and ATA6286 devices also include features such as integrated temperature sensors with shut-down mode, and a 90-kHz slow-oscillation mode for timer wake-up in Sleep mode. They also include LF (low frequency) inputs with several header options.

Low Power To The Hilt

These power-managed ICs are also optimized to ensure low current draw. In Sleep mode it's as low as 0.5-µA, and maximum Sleep mode current is 0.85-µA (at 85degrees C) in the chip's 90-kHz slow-oscillation mode.

Current draw during sensor measurement is as low as 200-µA. That's about 10 times less than piezo-resistive sensor systems. In Transmission mode, typical current is 8.5-mA (putting out 6-dBm, or 4-mW, of RF power).

Finally, the IC's programmable 125-kHz wake-up receiver channel draws less then 1.7-µA in its active listening mode.

Price And Availability

Atmel indicates samples, in 5 x 5-mm QFN32 packages, are available now, with high-volume production slated for mid-2007.

Pricing for both the ATA6285 and ATA6286 starts at about $2.60 a pop (in 50,000 piece quantities).

Click here for a preliminary datasheet (in Adobe Acrobat .PDF format).

For more details, contact Atmel Corp., 2325 Orchard Parkway, San Jose, Calif. 95131. Phone: 408-441-0311. Fax: 408-487-2600.

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

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