ATA5823/ATA5824 UHF ASK/FSK Transceiver DATASHEET Features ● High FSK sensitivity: –105.5dBm at 20Kbit/s/–109dBm at 2.4Kbit/s (433.92MHz) ● High ASK sensitivity: –111.5dBm at 10Kbit/s/–116dBm at 2.4Kbit/s (100% ASK, carrier level 433.92MHz) ● Low supply current: 10.5mA in RX and TX mode (3V/TX with 5dBm/433.92MHz) ● Data rate 1 to 20Kbit/s Manchester FSK, 1 to 10Kbit/s Manchester ASK ● ASK/FSK receiver uses a low IF architecture with high selectivity, blocking and low intermodulation (typical 3dB blocking 55.5dBC at ±750kHz/60.5dBC at ±1.5MHz and 67dBC at ±10MHz, system I1dBCP = –30dBm/system IIP3 = –20dBm) ● Wide bandwidth AGC to handle large outband blockers above the system I1dBCP ● 226kHz IF (intermediate frequency) with 30dB image rejection and 220kHz system bandwidth to support TPM transmitters using Atmel® ATA5756/ATA5757 transmitters with standard crystals ● Transmitter uses closed loop FSK modulation with fractional-N synthesizer with high PLL bandwidth and an excellent isolation between PLL and PA ● Tolerances of XTAL compensated by fractional-N synthesizer with 800Hz RF resolution ● Integrated RX/TX-switch, single-ended RF input and output ● RSSI (received signal strength indicator) ● Communication to microcontroller with SPI interface working at 500kBit/s maximum ● Configurable self polling and RX/TX protocol handling with FIFO-RAM buffering of received and transmitted data ● 1 push button input and 1 wake-up input are active in power-down mode ● Integrated XTAL capacitors ● PA efficiency: up to 38% (433.92MHz/10dBm/3V) ● Low In-band sensitivity change of typically ±2.0dB within ±75kHz center frequency change in the complete temperature and supply voltage range

● Fully integrated PLL with low phase noise VCO, PLL loop filter and full support of multi-channel operation with arbitrary channel distance due to fractional-N synthesizer ● Sophisticated threshold control and quasi-peak detector circuit in the data slicer ● 433.92MHz, and 315MHz without external VCO and PLL components ● Efficient XTO start-up circuit (> –1.5kΩ worst case start impedance) ● Changing of modulation type ASK/FSK and data rate without component changes to allow different modulation schemes in TPM and RKE ● Minimal external circuitry requirements for complete system solution ● Adjustable...

General Description The Atmel® ATA5823/ATA5824 is a highly integrated UHF ASK/FSK multi-channel half-duplex transceiver with low power consumption supplied in a small 7mm × 7mm QFN48 package. The receive part is built as a fully integrated low-IF receiver, whereas direct PLL modulation with the fractional-N synthesizer is used for FSK transmission and switching of the power amplifier for ASK transmission. The device supports data rates of 1Kbit/s to 20Kbit/s (FSK) and 1Kbit/s to 10Kbit/s (ASK) in Manchester, Bi-phase and other codes in transparent mode. The Atmel ATA5824 can be used in the 433MHz...

RX_ACTIVE N_PWR_ON DVCC CS_POL Resistor to adjust output power Selects RF input/output frequency range Not connected Pin to select output power Power supply input for voltage range 4.4V to 5.6V Power supply input for voltage range 2.15V to 3.6V Test input, at GND during operation Blocking of the digital voltage supply Blocking of the analog voltage supply Internal Programmable Resistor to adjust output power

Test input, at GND during operation Reference crystal Reference crystal Microcontroller interface supply voltage Programmable output Interrupt request Clock output to connect a microcontroller Serial data out/transparent mode data out Serial data in/transparent mode data in Serial clock Test output open during operation Chip select for serial interface Switch pin to decouple LNA in TX mode (RKE mode) Output of the RSSI amplifier Capacitor to adjust the lower cut-off frequency data filter Input to switch on the system (active high) Polarity of the serial clock Phase of the serial clock Keyboard...

Figure 2-2. Block Diagram AVCC Digital Control Logic Power Supply Frontend Enable RX/TX switch Fractional-N frequency synthesizer Signal Processing (Mixer IF-filter IF-amplifier FSK/ASK Demodulator, Data filter Data Slicer) FREQ FREF TX/RXData buffer Control register Status register Polling circuit Bit-check logic Synchronous logic (Full duplex operation mode) Switches Regulators Wake-up Reset PWR_ON N_PWR_ON Microcontroller interface

Typical Key Fob Application for Bi-directional RKE Figure 3-1. Typical Key Fob Application for Bi-directional RKE with 5dBm TX Power, 433.92MHz C11 Loop antenna PWR_H SETPWR Figure 3-1 shows a typical 433.92MHz RKE key fob application. The external components are 10 capacitors, 1 resistor, 2 inductors and a crystal. C1 to C3 are 68nF voltage supply blocking capacitors. C5 is a 10nF supply blocking capacitor. C6 is a 15nF fixed capacitor used for the internal quasi-peak detector and for the high-pass frequency of the data filter. C7 to C11 are RF matching capacitors in the range of 1pF to 33pF....

Typical Car Application for Bi-directional RKE Figure 4-1. Typical Car Application for Bi-directional RKE with 10dBm TX Power, 433.92MHz L3 R_PWR PWR_H Figure 4-1 shows a typical 433.92MHz VCC = 4.4V to 5.25V RKE car application. The external components are 11 capacitors, 1 resistor, 4 inductors, a SAW filter and a crystal. C1, C3 and C4 are 68nF voltage supply blocking capacitors. C2 is a 2.2µF supply blocking capacitor for the internal voltage regulator. C5 is a 10nF supply blocking capacitor. C6 is a 15nF fixed capacitor used for the internal quasi-peak detector and for the high-pass frequency...

RF Transceiver in Half-duplex Mode According to Figure 2-2 on page 6, the RF transceiver consists of an LNA (Low-Noise Amplifier), PA (Power Amplifier), RX/TX switch, fractional-N frequency synthesizer and the signal processing part with mixer, IF filter, IF amplifier with analog RSSI, FSK/ASK demodulator, data filter and data slicer. In receive mode the LNA pre-amplifies the received signal which is converted down to 226kHz intermediate frequency (IF), filtered and amplified before it is fed into an FSK/ASK demodulator, data filter and data slicer. The RSSI (Received Signal Strength Indicator)...