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PDF ATA5746 Data sheet ( Hoja de datos )
| Número de pieza | ATA5746 | |
| Descripción | (ATA5745 / ATA5746) UHF ASK/FSK Receiver | |
| Fabricantes | ATMEL Corporation | |
| Logotipo |  |
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Features
• Transparent RF Receiver ICs for 315 MHz (ATA5746) and 433.92 MHz (ATA5745) With
High Receiving Sensitivity
• Fully Integrated PLL With Low Phase Noise VCO, PLL, and Loop Filter
• High FSK/ASK Sensitivity:–105 dBm (ATA5746, FSK, 9.6 Kbits/s, Manchester, BER 10-3)
–114 dBm (ATA5746, ASK, 2.4 Kbits/s, Manchester, BER 10-3)
–104 dBm (ATA5745, FSK, 9.6 Kbits/s, Manchester, BER 10-3)
–113 dBm (ATA5745, ASK, 2.4 Kbits/s, Manchester, BER 10-3)
• Supply Current: 6.5 mA in Active Mode (3V, 25°C, ASK Mode)
• Data Rate: 1 Kbit/s to 10 Kbits/s Manchester ASK, 1 Kbit/s to 20 Kbits/s Manchester
FSK With Four Programmable Bit Rate Ranges
• Switching Between Modulation Types ASK/FSK and Different Data Rates Possible in
≤1 ms Typically, Without Hardware Modification on Board to Allow Different Modulation
Schemes for RKE, TPMS
• Low Standby Current: 50 µA at 3V, 25°C
• ASK/FSK Receiver Uses a Low-IF Architecture With High Selectivity, Blocking, and
Low Intermodulation (Typical 3-dB Blocking 68.0 dBC at ±3 MHz/74.0 dBC at
±20.0 MHz, System I1dBCP = –31 dBm/System IIP3 = –24 dBm)
• Telegram Pause Up to 52 ms Supported in ASK Mode
• Wide Bandwidth AGC to Handle Large Out-of-band Blockers above the System I1dBCP
• 440-kHz IF Frequency With 30-dB Image Rejection and 420-kHz IF Bandwidth to
Support PLL Transmitters With Standard Crystals or SAW-based Transmitters
• RSSI (Received Signal Strength Indicator) With Output Signal Dynamic Range of 65 dB
• Low In-band Sensitivity Change of Typically ±2.0 dB Within ±160-kHz Center
Frequency Change in the Complete Temperature and Supply Voltage Range
www.DataSheet4U.com
• Sophisticated Threshold Control and Quasi-peak Detector Circuit in the Data Slicer
• Fast and Stable XTO Start-up Circuit (> –1.4 kΩ Worst-case Start Impedance)
• Clock Generation for Microcontroller
• ESD Protection at all Pins (±4 kV HBM, ±200V MM, ±500V FCDM)
• Dual Supply Voltage Range: 2.7V to 3.3V or 4.5V to 5.5V
• Temperature Range: –40°C to +105°C
• Small 5 mm × 5 mm QFN24 Package
UHF ASK/FSK
Receiver
ATA5745
ATA5746
Preliminary
Applications
• Automotive Keyless Entry and Tire Pressure Monitoring Systems
• Alarm, Telemetering and Energy Metering Systems
Benefits
• Supports Header and Blanking Periods of Protocols Common in RKE and TPM
Systems (Up to 52 ms in ASK Mode)
• All RF Relevant Functions are Integrated. The Single-ended RF Input is Suited for Easy
Adaptation to λ / 4 or Printed-loop Antennas
• Allows a Low-cost Application With Only 8 Passive Components
• Suitable for use in a Receiver for Joint RKE and TPMS
• Optimal Bandwidth Maximizes Sensitivity while Maintaining SAW Transmitter
Compatibility
• Clock Output Provides an External Microcontroller Crystal-precision Time Reference
• Well Suited for Use With PLL Transmitter ATA5756/ATA5757
4596A–RKE–05/06
1 page  
ATA5745/ATA5746 [Preliminary]
2. RF Receiver
As seen in Figure 1-3 on page 4, the RF receiver consists of a low-noise amplifier (LNA), a local
oscillator, 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 a
440-kHz intermediate frequency (IF), then filtered and amplified before it is fed into an FSK/ASK
demodulator, data filter, and data slicer. The received signal strength indicator (RSSI) signal is
available at the pin RSSI.
2.1 Low-IF Receiver
The receive path consists of a fully integrated low-IF receiver. It fulfills the sensitivity, blocking,
selectivity, supply voltage, and supply current specification needed to design an automotive inte-
grated receiver for RKE and TPM systems. A benefit of the integrated receive filter is that no
external components needed.
At 315 MHz, the ATA5745 receiver (433.92 MHz for the ATA5746 receiver) has a typical system
noise figure of 6.0 dB (7.0 dB), a system I1dBCP of –31 dBm (–30 dBm), and a system IIP3 of
–24 dBm (–23 dBm). The signal path is linear for out-of-band disturbers up to the I1dBCP and
hence there is no AGC or switching of the LNA needed, and a better blocking performance is
achieved. This receiver uses an IF (intermediate frequency) of 440 kHz, the typical image rejec-
tion is 30 dB and the typical 3-dB IF filter bandwidth is 420 kHz (fIF = 440 kHz ± 210 kHz,
flo_IF = 230 kHz and fhi_IF = 650 kHz). The demodulator needs a signal-to-noise ratio of 8.5 dB for
10 Kbits/s Manchester with ±38 kHz frequency deviation in FSK mode, thus, the resulting sensi-
tivity at 315 MHz (433.92 MHz) is typically –105 dBm (–104 dBm).
Due to the low phase noise and spurs of the synthesizer together with the 8th-order integrated IF
filter, the receiver has a better selectivity and blocking performance than more complex double
superhet receivers, without using external components and without numerous spurious receiv-
ing frequencies.
A low-IF architecture is also less sensitive to second-order intermodulation (IIP2) than direct
conversion receivers where every pulse or amplitude modulated signal (especially the signals
from TDMA systems like GSM) demodulates to the receiving signal band at second-order
non-linearities.
4596A–RKE–05/06
5
5 Page 
ATA5745/ATA5746 [Preliminary]
2.5 RX Supply Current Versus Temperature and Supply Voltage
Table 2-7 shows the typical supply current of the receiver in Active mode versus supply voltage
and temperature with VS = VS3V_AVCC = VS5V.
Table 2-6. Measured Current in Active Mode ASK
VS = VS3V_AVCC = VS5V
2.7V
Tamb = –40°C
Tamb = 25°C
Tamb = 105°C
5.4 mA
6.4 mA
7.4 mA
3.0V
5.5 mA
6.5 mA
7.5 mA
3.3V
5.6 mA
6.6 mA
7.6 mA
Table 2-7. Measured Current in Active Mode FSK
VS = VS3V_AVCC = VS5V
2.7V
Tamb = –40°C
Tamb = 25°C
Tamb = 105°C
5.6 mA
6.6 mA
7.6 mA
3.0V
5.7 mA
6.7 mA
7.7 mA
3.3V
5.8 mA
6.8 mA
7.8 mA
2.6 Blocking, Selectivity
As can be seen in Figure 2-6 on page 11, and Figure 2-7 and Figure 2-8 on page 12, the
receiver can receive signals 3 dB higher than the sensitivity level in the presence of large block-
ers of –34.5 dBm or –28 dBm with small frequency offsets of ±3 MHz or ±20 MHz.
Figure 2-6, and Figure 2-7 on page 12 show the narrow-band blocking, and Figure 2-8 on page
12 shows the wide-band blocking characteristic. The measurements were done with a useful
signal of 315 MHz, FSK, 10 Kbits/s, ±38 kHz, Manchester, BR_Range2 with a level of
–105 dBm + 3 dB = –102 dBm, which is 3 dB above the sensitivity level. The figures show how
much larger than –102 dBm a continuous wave signal can be, until the BER is higher than 10–3.
The measurements were done at the 50Ω input shown in Figure 2-1 on page 6. At 3 MHz, for
example, the blocker can be 67.5 dBC higher than –102 dBm, or
–102 dBm + 67.5 dBC = –34.5 dBm.
Figure 2-6.
Close-in 3-dB Blocking Characteristic and Image Response at 315 MHz
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
-10.0
-2.0
-1.5 -1.0 -0.5 0.0 0.5 1.0
1.5
Distance from Interfering to Receiving Signal (MHz)
2.0
4596A–RKE–05/06
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet ATA5746.PDF ] | |
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