ATA5423 ATMEL Corporation, ATA5423 Datasheet - Page 7

• Manufacturer Part Number: ATA5423
• Manufacturer: ATMEL Corporation

2. Application Circuits
2.1
Figure 2-1.
4841A–RKE–02/05
Typical Remote Control Unit Application with 1 Battery
Loop antenna
Typical Remote Control Unit Application, 433.92 MHz, 1 Battery
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
C9
7
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
433_N868
NC
NC
NC
RF_IN
NC
NC
R_PWR
PWR_H
RF_OUT
NC
NC
C2
C1
ATA5423/ATA5425/
ATA5428/ATA5429
1
is typically 22 k 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
ATA5423/25/28/29 [Preliminary]
5
is a 10 nF supply blocking capacitor. C
SDO_TMDO
DEM_OUT
SDI_TMDI
N_RESET
CDEM
VSINT
RSSI
SCK
CLK
IRQ
NC
CS
C6
XTAL2
13.25311 MHz
C3
VCC
Sensor
µC
VSS
6
1
is a 15 nF fixed
to C
4
are 68 nF
7