3

ATA5745C/ATA5746C [DATASHEET]

9249C–RKE–10/14

1.

General Description

small QFN24 package (body 5mm

× 5mm, pitch 0.65mm). Atmel ATA5745C is used in the 433MHz to 435MHz band of

operation, and Atmel ATA5746C in 313MHz to 317MHz. The IC combines the functionality of remote keyless entry (RKE -

typically low bit rate ASK) and tire pressure monitoring (TPM - typically high bit rate FSK) into one receiver under the control

For improved image rejection and selectivity, the IF frequency is fixed to 440kHz. The IF block uses an 8th-order band pass

yielding a receive bandwidth of 420kHz. This enables the use of the receiver in both SAW- and PLL-based transmitter

systems utilizing various types of data-bit encoding such as pulse width modulation, Manchester modulation, variable pulse

to the receiver’s ability to hold the current data slicer threshold for up to 52ms when incoming RF telegrams contain a

blanking interval. This feature eliminates erroneous noise from appearing on the demodulated data output pin, and simplifies

software decoding algorithms. The decoding of the data stream must be carried out by a connected microcontroller device.

Because of the highly integrated design, the only required RF components are for the purpose of receiver antenna matching.

Atmel ATA5745C and Atmel ATA5746C support Manchester bit rates of 1Kbit/s to 10Kbits/s in ASK and 1Kbit/s to 20Kbits/s

in FSK mode. The four discrete bit rate passbands are selectable and cover 1.0Kbit/s to 2.5Kbits/s, 2.0Kbits/s to 5.0Kbits/s,

4.0Kbits/s to 10.0Kbits/s, and 8.0Kbits/s to 10.0Kbits/s or 20.0Kbits/s (for ASK or FSK, respectively). The receiver contains

an RSSI output to provide an indication of received signal strength and a SENSE input to allow the customer to select a

threshold below which the DATA signal is gated off. ASK/FSK and bit rate ranges are selected by the connected

microcontroller device via pins ASK_NFSK, BR0, and BR1.

Figure 1-1. System Block Diagram

(LNA, Mixer,

VCO, PLL,

IF Filter,

RSSI Amp.,

Demodulator)

RF Receiver

ATA5745C/ATA5746C

Antenna

XTO

Microcontroller

Microcontroller

Interface

4 ... 8

Power

Supply

Digital Control

Logic