Features
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Multi Channel Half–duplex Transceiver with Approximately ±2.5 MHz Programmable
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Tuning Range
High FSK Sensitivity: –106 dBm at 20 kBaud/–109.5 dBm at 2.4 kBaud (433.92 MHz)
High ASK Sensitivity: –112.5 dBm at 10 kBaud/–116.5 dBm at 2.4 kBaud (433.92 MHz)
Low Supply Current: 10.5 mA in RX and TX Mode (3 V/TX with 5 dBm)
Data Rate: 1 to 20 kBaud Manchester FSK, 1 to 10 kBaud Manchester ASK
ASK/FSK Receiver Uses a Low–IF Architecture with High Selectivity, Blocking, and
Low Intermodulation (Typical Blocking 55 dB at ±750 kHz/61 dB at ±1.5 MHz and
70 dB at ±10 MHz, System I1dBCP = –30 dBm/System IIP3 = –20 dBm)
226 kHz IF Frequency with 30 dB Image Rejection and 170 kHz Usable IF Bandwidth
(TBD)
Transmitter Uses Closed Loop Fractional–N Synthesizer for FSK Modulation with a
High PLL Bandwidth and an Excellent Isolation between PLL/VCO and PA
Tolerances of XTAL Compensated by Fractional–N Synthesizer with 800 Hz 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 Maximum 500 kBit/s
Configurable Self Polling and RX/TX Protocol Handling with FIFO–RAM Buffering of
Received and Transmitted Data
5 Push Button Inputs and One Wake–up Input are Active in Power–down Mode
Integrated XTAL Capacitors
PA Efficiency: up to 38% (433.92 MHz/10 dBm/3 V)
Low In–band Sensitivity Change of Typically ±1.8 dB within ±58 kHz Center Frequency
Change in the Complete Temperature and Supply Voltage Range (TBD)
Supply Voltage Switch, Supply Voltage Regulator, Reset Generation, Clock/Interrupt
Generation and Low Battery Indicator for Microcontroller
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
Power Management via Different Operation Modes
315 MHz, 345 MHz, 433.92 MHz, 868.3 MHz and 915 MHz without External VCO and PLL
Components
Inductive Supply with Voltage Regulator if Battery is Empty (AUX Mode)
Efficient XTO Start–up Circuit (> –1.5 kΩ Worst Case Real Start–up Impedance)
Changing of Modulation Type ASK/FSK and Data Rate without Component Changes
Minimal External Circuitry Requirements for Complete System Solution
Adjustable Output Power: 0 to 10 dBm Adjusted and Stabilized with External Resistor
ESD Protection at all Pins (2 kV HBM, 200 V MM, TBD FCDM)
Supply Voltage Range: 2.4 V to 3.6 V or 4.4 V to 6.6 V
Temperature Range: –40°C to +85°C
Small 7
×
7 mm QFN48 Package
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UHF ASK/FSK
Transceiver
ATA5423
ATA5425
ATA5428
ATA5429
Preliminary
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Rev. 4841A–RKE–02/05
Applications
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Consumer Industrial Segment
Access Control Systems
Remote Control Systems
Alarm and Telemetry Systems
Energy Metering
Home Automation
Benefits
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Low System Cost Due to Very High System Integration Level
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Only One Crystal Needed in System
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Less Demanding Specification for the Microcontroller Due to Handling of Power–down Mode,
Delivering of Clock, Reset, Low Battery Indication and Complete Handling of Receive/Transmit
Protocol and Polling
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Single–ended Design with High Isolation of PLL/VCO from PA and the Power Supply Allows a
Loop Antenna in the Remote Control Unit to Surround the Whole Application
2
ATA5423/25/28/29 [Preliminary]
4841A–RKE–02/05
ATA5423/25/28/29 [Preliminary]
1. General Description
The ATA5423/25/28/29 is a highly integrated UHF ASK/FSK multi–channel half–duplex trans-
ceiver with low power consumption supplied in a small 7 x 7 mm QFN48 package. The receive
part is built as a fully integrated low–IF receiver, whereas direct PLL modulation with the frac-
tional–N synthesizer is used for FSK transmission and switching of the power amplifier for ASK
transmission.
The device supports data rates of 1 kBaud to 20 kBaud (FSK) and 1 kBaud to 10 kBaud (ASK)
in Manchester, Bi–phase and other codes in transparent mode. The ATA5428 can be used in
the 431.5 MHz to 436.5 MHz and in the 862 MHz to 872 MHz bands, the ATA5423 in the
312.5 MHz to 317.5 MHz band, the ATA5425 in the 342.5 MHz to 347.5 MHz band and the
ATA5429 in the 912.5 MHz to 917.5 MHz band. The very high system integration level results in
a small number of external components needed.
Due to its blocking and selectivity performance, together with the additional 15 dB to 20 dB loss
and the narrow bandwidth of a typical loop antenna in a remote control unit, a bulky blocking
SAW is not needed in the remote control unit. Additionally, the building blocks needed for a typi-
cal remote control and access control system on both sides (the base and the mobile stations)
are fully integrated.
Its digital control logic with self–polling and protocol generation enables a fast challenge–
response system without using a high–performance microcontroller. Therefore, the
ATA5423/ATA5425/ATA5428/ATA5429 contains a FIFO buffer RAM and can compose and
receive the physical messages themselves. This provides more time for the microcontroller to
carry out other functions such as calculating crypto algorithms, composing the logical messages,
and controlling other devices. Therefore, a standard 4–/8–bit microcontroller without special
periphery and clocked with the CLK output of about 4.5 MHz is sufficient to control the communi-
cation link. This is especially valid for passive entry and access control systems, where within
less than 100 ms several challenge–response communications with arbitration of the communi-
cation partner have to be handled.
It is hence possible to design bi–directional remote control and access control systems with a
fast challenge–response crypto function, with the same PCB board size and with the same cur-
rent consumption as uni–directional remote control systems.
Figure 1-1.
System Block Diagram
ATA5423/25/28/29
RF Transceiver
Antenna
Digital Control
Logic
Power
Supply
µC
Matching/
RF Switch
4 ... 8
µC_Interface
XTO
3
4841A–RKE–02/05
Figure 1-2.
Pinning QFN48
NC
NC
RX_ACTIVE
T1
T2
T3
T4
T5
PWR_ON
RX_TX1
RX_TX2
CDEM
NC
NC
NC
RF_IN
NC
433_N868
NC
R_PWR
PWR_H
RF_OUT
NC
NC
48 47 46 45 44 43 42 41 40 39 38 37
36
1
35
2
34
3
33
4
32
5
ATA5423/ATA5425
31
6
ATA5428/ATA5429
30
7
29
8
28
9
27
10
26
11
25
12
13 14 15 16 17 18 19 20 21 22 23 24
NC
NC
NC
AVCC
VS2
VS1
VAUX
TEST1
DVCC
VSOUT
TEST2
XTAL1
RSSI
CS
DEM_OUT
SCK
SDI_TMDI
SDO_TMDO
CLK
IRQ
N_RESET
VSINT
NC
XTAL2
Table 1-1.
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Pin Description
Symbol
NC
NC
NC
RF_IN
NC
433_N868
NC
R_PWR
PWR_H
RF_OUT
NC
NC
NC
NC
NC
AVCC
VS2
VS1
VAUX
TEST1
DVCC
Function
Not connected
Not connected
Not connected
RF input
Not connected
Selects RF input/output frequency range
Not connected
Resistor to adjust output power
Pin to select output power
RF output
Not connected
Not connected
Not connected
Not connected
Not connected
Blocking of the analog voltage supply
Power supply input for voltage range 4.4 V to 6.6 V
Power supply input for voltage range 2.4 V to 3.6 V
Auxiliary supply voltage input
Test input, at GND during operation
Blocking of the digital voltage supply
4
ATA5423/25/28/29 [Preliminary]
4841A–RKE–02/05
ATA5423/25/28/29 [Preliminary]
Table 1-1.
Pin
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Pin Description (Continued)
Symbol
VSOUT
TEST2
XTAL1
XTAL2
NC
VSINT
N_RESET
IRQ
CLK
SDO_TMDO
SDI_TMDI
SCK
DEM_OUT
CS
RSSI
CDEM
RX_TX2
RX_TX1
PWR_ON
T5
T4
T3
T2
T1
RX_ACTIVE
NC
NC
GND
Function
Output voltage power supply for external devices
Test input, at GND during operation
Reference crystal
Reference crystal
Not connected
Microcontroller interface supply voltage
Output pin to reset a connected microcontroller
Interrupt request
Clock output to connect a microcontroller
Serial data out/transparent mode data out
Serial data in/transparent mode data in
Serial clock
Demodulator open drain output signal
Chip select for serial interface
Output of the RSSI amplifier
Capacitor to adjust the lower cut
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off frequency data filter
GND pin to decouple LNA in TX mode
Switch pin to decouple LNA in TX mode
Input to switch on the system (active high)
Key input 5 (can also be used to switch on the system (active low))
Key input 4 (can also be used to switch on the system (active low))
Key input 3 (can also be used to switch on the system (active low))
Key input 2 (can also be used to switch on the system (active low))
Key input 1 (can also be used to switch on the system (active low))
Indicates RX operation mode
Not connected
Not connected
Ground/backplane
5
4841A–RKE–02/05
