ATA5423_06 ATMEL [ATMEL Corporation], ATA5423_06 Datasheet - Page 7

• Manufacturer Part Number: ATA5423_06
• Description: UHF ASK/FSK Transceiver
• Manufacturer: ATMEL [ATMEL Corporation]

2. Application Circuits
2.1
Figure 2-1.
4841C–WIRE–05/06
Typical Remote Control Unit Application with 1 Li Battery (3V)
Loop antenna
Typical Remote Control Unit Application, 433.92 MHz, 1 Li Battery (3V)
AVCC
C10
L2
Figure 2-1
external components are 11 capacitors, 1 resistor, 2 inductors and a crystal. C
voltage supply blocking capacitors. C
capacitor used for the internal quasi-peak detector and for the high-pass frequency of the data
filter. C
tor of about 5.6 nH to 56 nH. L
the crystal is integrated. R
loop antenna’s quality factor is somewhat reduced by this application due to the quality factor of
L
robust design with a bandwidth that is broad enough for production tolerances. Due to the sin-
gle-ended and ground-referenced design, the loop antenna can be a free-form wire around the
application as it is usually employed in remote control uni-directional systems. The
ATA5423/ATA5425/ATA5428/ATA5429 provides sufficient isolation and robust pulling behavior
of internal circuits from the supply voltage as well as an integrated VCO inductor to allow this.
Since the efficiency of a loop antenna is proportional to the square of the surrounded area it is
beneficial to have a large loop around the application board with a lower quality factor in order to
relax the tolerance specification of the RF components and to get a high antenna efficiency in
spite of their lower quality factor.
L1
2
and the RX/TX switch. On the other hand, this lower quality factor is necessary to have a
C5
C11
C8
7
C9
to C
R1
shows a typical 433.92 MHz Remote Control Unit application with one battery. The
11
are RF matching capacitors in the range of 1 pF to 33 pF. L1 is a matching induc-
C7
RF_IN
RF_OUT
NC
NC
NC
NC
433_N868
NC
R_PWR
PWR_H
NC
NC
C1
C2
ATA5423/ATA5425/
ATA5428/ATA5429
1
is typically 22 kΩ and sets the output power to about 5.5 dBm. The
+
2
Litihum-
is a feed inductor of about 120 nH. A load capacitor of 9 pF for
Cell
C4
5
is a 10 nF supply blocking capacitor. C
SDO_TMDO
DEM_OUT
SDI_TMDI
N_RESET
CDEM
VSINT
RSSI
SCK
CLK
IRQ
CS
NC
C6
XTAL2
13.25311 MHz
ATA5423/25/28/29
C3
VCC
48/88/168
ATmega
Sensor
VSS
6
1
is a 15 nF fixed
to C
4
are 68 nF
7