ATA5423 ATMEL Corporation, ATA5423 Datasheet - Page 3

• Manufacturer Part Number: ATA5423
• Manufacturer: ATMEL Corporation

1. General Description
4841A–RKE–02/05
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.
Antenna
RF Switch
Matching/
System Block Diagram
RF Transceiver
ATA5423/25/28/29 [Preliminary]
ATA5423/25/28/29
Digital Control
Logic
XTO
µC_Interface
Supply
Power
4 ... 8
µC
3