Atmel has introduced two new single-chip, small footprint (5 mm x 5 mm) UHF ASK/FSK receiver ICs for automotive RF applications such as remote keyless entry (RKE) and tire pressure monitoring systems (TPMS).
The ATA5745 operates at 433 MHz to 435 MHz and the ATA5746 at 313 MHz to 315 MHz. Both are manufactured using Atmel's UHF6S new RF BiCMOS process, which enables especially small designs. Both feature fully integrated filters and are said to combine large bandwidth and excellent receiving selectivity. Image rejection is typically 30 dB.
The ATA5745 and ATA5746 are transparent receiver ICs that operate with a separate microcontroller for bit check and polling modes. Each chip consists of an integrated IF filter, low-phase noise VCO, PLL and loop filter. Whether deployed in low-cost or sophisticated applications, the ATA5745 and ATA5746 are said to need few external devices – typically eight passive components, a crystal, and an RF antenna – and no external filters. The chips’ large oscillation margin permits the use of very low-cost crystals, according to Atmel.
The chips enable fast switching between TPMS and RKE signals and can be used in unified RKE/TPMS environments with different system definitions; eliminating the need for separate RKE and TPMS ICs. They can change modulation between ASK and FSK and between data rates without component changes when receiving different TPMS/RKE modulation schemes or data rates. Typical switching between ASK/FSK modulation types and different data rates is possible in less than 1 ms.
Both devices can be operated in 1 to 20 Kb/s Manchester FSK mode with four different microcontroller-selectable baud rate ranges, without hardware modification. Active current consumption is specified at approximately 6.5 mA in receive mode based on single-ended RF input for easy adaptation of lambda/4 or printed loop antennas. The devices 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. Samples are available in QFN24 packages.