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Features
•
Minimal External Circuitry Requirements, No RF Components on the PC Board Except
Matching to the Receiver Antenna
•
High Sensitivity, Especially at Low Data Rates
•
Sensitivity Reduction Possible Even While Receiving
•
Fully Integrated VCO
•
Low Power Consumption Due to Configurable Self Polling with a Programmable Time
Frame Check
•
Supply Voltage 4.5V to 5.5V
•
Operating Temperature Range –40°C to +105°C
Single-ended RF Input for Easy Adaptation to λ / 4 Antenna or Printed Antenna on PCB
•
•
Low-cost Solution Due to High Integration Level
•
ESD Protection According to MIL-STD. 883 (4 KV HBM) Except Pin POUT (2 KV HBM)
•
High Image Frequency Suppression due to 1 MHz IF in Conjunction with a SAW
Front-end Filter
– Up to 40 dB is Thereby Achievable with Newer SAWs
•
Programmable Output Port for Sensitivity Selection or for Controlling External
Periphery
•
Communication to the Microcontroller Possible via a Single, Bi-directional Data Line
•
Power Management (Polling) is also Possible by Means of a Separate Pin via the
Microcontroller
•
2 Different IF Bandwidth Versions are Available (300 kHz and 600 kHz)
1. Description
The ATA3741 is a multi-chip PLL receiver device supplied in an SO20 package. It has
been specially developed for the demands of RF low-cost data transmission systems
with low data rates from 1 kBaud to 10 kBaud (1 kBaud to 3.2 kBaud for FSK) in
Manchester or Bi-phase code. The receiver is well-suited to operate with Atmel's PLL
RF transmitter U2741B. Its main applications are in the areas of telemetering, security
technology, and keyless-entry systems. It can be used in the frequency receiving
range of f
= 300 MHz to 450 MHz for ASK or FSK data transmission. All the state-
0
ments made below refer to 433.92-MHz and 315-MHz applications.
UHF ASK
Receiver IC
ATA3741
4899B–RKE–10/06
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Related Manuals for Atmel ATA3741 Series
Summary of Contents for Atmel ATA3741 Series
- Page 1 1 kBaud to 10 kBaud (1 kBaud to 3.2 kBaud for FSK) in Manchester or Bi-phase code. The receiver is well-suited to operate with Atmel's PLL RF transmitter U2741B. Its main applications are in the areas of telemetering, security technology, and keyless-entry systems.
- Page 2 Figure 1-1. System Block Diagram UHF ASK/FSK UHF ASK/FSK Remote control receiver Remote control transmitter 1 Li cell U2741B ATR3741 1...3 Demod Control Encoder ATARx9x Antenna Keys Antenna Power amp. Figure 1-2. Block Diagram FSK/ASK 50 kΩ FSK/ASK DEMOD_OUT Demodulator and data filter CDEM DATA...
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Page 3: Pin Configuration
ATA3741 2. Pin Configuration Figure 2-1. Pinning SO20 SENS DATA FSK/ASK ENABLE CDEM TEST AVCC POUT AGND MODE DGND DVCC MIXVCC LNAGND LFGND LNA_IN LFVCC Table 2-1. Pin Description Symbol Function SENS Sensitivity-control resistor FSK/ASK Selecting FSK/ASK. Low: FSK, High: ASK CDEM Lower cut-off frequency data filter AVCC... -
Page 4: Rf Front End
3. RF Front End The RF front end of the receiver is a heterodyne configuration that converts the input signal into a 1-MHz IF signal. As seen in the block diagram, the front end consists of an LNA (low noise amplifier), LO (local oscillator), a mixer, and an RF amplifier. - Page 5 ATA3741 is determined by the RF input frequency f and the IF frequency f using the following for- mula: – To determine f , the construction of the IF filter must be considered at this point. The nominal IF frequency is f = 1 MHz.
- Page 6 Figure 3-2. Input Matching Network With SAW Filter LNAGND LNAGND ATA3741 ATA3741 LNA_IN LNA_IN 8.2p 100p = 433.92 MHz = 315 MHz 100p TOKO LL2012 TOKO LL2012 27NJ F47NJ TOKO LL2012 TOKO LL2012 F33NJ F82NJ B3555 B3551 IN_GND OUT_GND IN_GND OUT_GND CASE_GND CASE_GND...
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Page 7: Analog Signal Processing
The ATA3741 is available with 2 different IF bandwidths. ATA3741-M2, the version with = 300 kHz, is well suited for ASK systems where Atmel’s PLL transmitter U2741B is used. The receiver ATA3741-M3 employs an IF bandwidth of B = 600 kHz. This version can be used together with the U2741B in FSK and ASK mode. - Page 8 FSK/ASK Demodulator and Data Filter The signal coming from the RSSI amplifier is converted into the raw data signal by the ASK/FSK demodulator. The operating mode of the demodulator is set via pin ASK/FSK. Logic “L” sets the demodulator to FSK, Logic “H” sets it into ASK mode. In ASK mode an automatic threshold control circuit (ATC) is employed to set the detection refer- ence voltage to a value where a good SNR is achieved.
- Page 9 ATA3741 When designing the system in terms of receiving bandwidth, the LO deviation must be consid- ered as it also determines the IF center frequency. The total LO deviation is calculated to be the sum of the deviation of the crystal and the XTO deviation of the ATA3741. Low-cost crystals are specified to be within ±100 ppm.
- Page 10 Figure 5-1. Generation of the Basic Clock Cycle MODE Divider :14/:10 L : USA (:10) H: Europe (:14) DVCC Pin MODE can now be set in accordance with the desired clock cycle T controls the fol- lowing application-relevant parameters: • Timing of the polling circuit including bit check •...
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Page 11: Polling Mode
ATA3741 Polling Mode As shown in Figure 3-2 on page 6, the receiver stays in polling mode in a continuous cycle of three different modes. In sleep mode, the signal processing circuitry is disabled for the time period T while consuming a low current of I . - Page 12 Figure 5-2. Polling Mode Flow Chart Sleep Mode: All circuits for signal processing are disabled. Only XTO and polling logic is enabled. Sleep: 5-bit word defined by Sleep0 to Sleep4 in Output level on pin IC_ACTIVE => low OPMODE register = Sleep ×...
- Page 13 ATA3741 Bit-check Mode In bit-check mode, the incoming data stream is examined to distinguish between a valid signal from a corresponding transmitter and signals due to noise. This is done by subsequent time frame checks where the distances between 2 signal edges are continuously compared to a pro- grammable time window.
- Page 14 Figure 5-5, Figure 5-6 Figure 5-7 illustrate the bit check for the default bit-check limits Lim_min = 14 and Lim_max = 24. When the IC is enabled, the signal processing circuits are enabled during T . The output of the ASK/FSK demodulator (Dem_out) is undefined during Startup that period.
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Page 15: Receiving Mode
ATA3741 5.3.2 Duration of the Bit Check If no transmitter signal is present during the bit check, the output of the ASK/FSK demodulator delivers random signals. The bit check is a statistical process and T varies for each check. Bitcheck Therefore, an average value for T is given in “Electrical Characteristics”. - Page 16 Figure 5-9. Debouncing of the Demodulator Output Dem_out DATA Lim_min ≤ CV_Lim < Lim_max tmin1 CV_Lim < Lim_min or CV_Lim ≥ Lim_max tmin2 Figure 5-10. Steady L State Limited DATA Output Pattern after Transmission Enable IC Bit check Dem_out DATA tmin2 DATA_L_max Sleep mode...
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Page 17: Configuration Of The Receiver
ATA3741 Figure 5-11. Timing Diagram of the OFF Command Via Pin DATA Out1 (microcontroller) DATA (U3741BM) Serial bi-directional data line Bit 1 ("1") Receiver (Start bit) Startup mode Sleep OFF command Figure 5-12. Timing Diagram of the OFF Command Via Pin ENABLE Doze Sleep ENABLE... - Page 18 Table 5-3 through Table 5-9 on page 20 illustrate the effect of the individual configuration words. The default configuration is labeled for each word. BR_Range sets the appropriate baud rate range. At the same time, it defines XLim. XLim is used to define the bit check limits T and T as shown in...
- Page 19 ATA3741 Table 5-5. Effect of the Configuration Bit VPOUT VPOUT Level of the Multi-purpose Output Port POUT POUT 0 (Default) Table 5-6. Effect of the Configuration Word Sleep Sleep Start Value for Sleep Counter = Sleep × X × 1024 × T Sleep4 Sleep3 Sleep2...
- Page 20 Table 5-8. Effect of the Configuration Word Lim_min Lim_min Lower Limit Value for Bit Check = Lim_min × XLim × T Lim_min < 10 is not applicable Lim_min 14 (Default) (USA: T = 228 µs, Europe: T = 232 µs) Lim_min Lim_min Table 5-9.
- Page 21 ATA3741 To indicate that condition, the receiver displays a reset marker (RM) at pin DATA after a reset. The RM is represented by the fixed frequency f at a 50% duty cycle. RM can be canceled via an “L” pulse t1 at pin DATA. The RM implies the following characteristics: •...
- Page 22 Figure 5-15. One-wire Connection to a Microcontroller ATA3741 Microcontroller Internal pull-up Bi-directional resistor data line DATA Out 1 (microcontroller) DATA (ATA3741) To start programming, the serial data line DATA is pulled to “L” by the microcontroller for the time period t1. When DATA has been released, the receiver becomes the master device. When the programming delay period t2 has elapsed, it emits 14 subsequent synchronization pulses with the pulse length t3.
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Page 23: Absolute Maximum Ratings
ATA3741 6. Absolute Maximum Ratings Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. - Page 24 8. Electrical Characteristics (Continued) All parameters refer to GND, T = –40°C to +105°C, V = 4.5V to 5.5V, f = 433.92 MHz and f = 315 MHz, unless otherwise specified. = 5V, T = 25°C) 6.76438-Mhz Oscillator 4.90625-Mhz Oscillator (Mode 1) (Mode 0) Variable Oscillator...
- Page 25 ATA3741 8. Electrical Characteristics (Continued) All parameters refer to GND, T = –40°C to +105°C, V = 4.5V to 5.5V, f = 433.92 MHz and f = 315 MHz, unless otherwise specified. = 5V, T = 25°C) 6.76438-Mhz Oscillator 4.90625-Mhz Oscillator (Mode 1) (Mode 0) Variable Oscillator...
- Page 26 9. Electrical Characteristics (Continued) All parameters refer to GND, T = –40°C to +105°C, V = 4.5V to 5.5V, f = 433.92 MHz and f = 315 MHz, unless otherwise specified. = 5V, T = 25°C) Parameters Test Conditions Symbol Min.
- Page 27 ATA3741 9. Electrical Characteristics (Continued) All parameters refer to GND, T = –40°C to +105°C, V = 4.5V to 5.5V, f = 433.92 MHz and f = 315 MHz, unless otherwise specified. = 5V, T = 25°C) Parameters Test Conditions Symbol Min.
- Page 28 9. Electrical Characteristics (Continued) All parameters refer to GND, T = –40°C to +105°C, V = 4.5V to 5.5V, f = 433.92 MHz and f = 315 MHz, unless otherwise specified. = 5V, T = 25°C) Parameters Test Conditions Symbol Min.
- Page 29 ATA3741 9. Electrical Characteristics (Continued) All parameters refer to GND, T = –40°C to +105°C, V = 4.5V to 5.5V, f = 433.92 MHz and f = 315 MHz, unless otherwise specified. = 5V, T = 25°C) Parameters Test Conditions Symbol Min.
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Page 30: Ordering Information
10. Ordering Information Extended Type Number Package Remarks ATA3741P2-TGSY SO20 2: IF bandwidth of 300 kHz, tube, Pb-free ATA3741P2-TGQY SO20 2: IF bandwidth of 300 kHz, taped and reeled, Pb-free ATA3741P3-TGSY SO20 3: IF bandwidth of 600 kHz, tube, Pb-free ATA3741P3-TGQY SO20 3: IF bandwidth of 600 kHz, taped and reeled, Pb-free... - Page 31 Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN ATMEL’S TERMS AND CONDI- TIONS OF SALE LOCATED ON ATMEL’S WEB SITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY...
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