ATA5823 ATMEL Corporation, ATA5823 Datasheet - Page 8

• Manufacturer Part Number: ATA5823
• Description: Uhf Ask/fsk Transceiver Ata5823 Ata5824
• Manufacturer: ATMEL Corporation

5. Typical Key Fob Application for Full-duplex PEG
Figure 5-1.
8
ATA5823/ATA5824
Typical Key Fob Application for Full-duplex PEG, 433.92 MHz
Loop antenna 2
C
20% overlap
6
Figure 5-1
10 capacitors, 1 resistor, 1 inductor and a crystal. C
capacitors. C
internal quasi-peak detector and for the high-pass frequency of the data filter. C
are RF matching capacitors in the range of 1 pF to 33 pF. L
C
causing amplitude modulation of the output power and a spurious rise of the transmitted signal.
R
integrated. R
in full-duplex mode and 5 dBm in half-duplex mode. The quality factor of the loop antenna 1 is
only reduced by the quality factor of L
ity factor of the loop antenna 2 is reduced to half due to the loading with the input impedance of
RF_IN. With well designed loop antennas and the correct degree of overlapping, the isolation
between RF_OUT and RF_IN is about 28 dB and the coupled output power from RF_OUT to
RF_IN is about –35 dBm. The decoupling of two loop antennas situated close to each other is
due to the effect that the magnetic flux from the part of loop antenna 1 that does not overlap and
that of the overlapping part has an opposite direction. Depending on the relative position
between the two antennas, a decoupling of 28 dB is achievable. Due to additional capacitive
coupling between the loops the position of the components C
The receive Sensitivity in full-duplex mode is reduced from –106 dBm without coupled
RF-Power at RF_IN to –96 dBm with –35 dBm coupled RF power at RF_IN.
Loop antenna 1
10
1
and C
C
is a 10 nF capacitor which is necessary to prevent that signals couple into the pin R_PWR,
5
AVCC
10
C
C
L
shows a typical 433.92 MHz PEG key fob application. The external components are
8
9
should be placed close to the R_PWR pin. A load capacitor of 9 pF for the crystal is
2
1
7
is typically 22 k and SETPWR is programmed to get an output power of –7 dBm
is a 10 nF supply blocking capacitor. C
C
7
R
C
1
10
NC
NC
NC
RF_IN
NC
433_N868
NC
R_PWR
PWR_H
RF_OUT
NC
NC
C
1
ATA5823/ATA5824
2
, the tolerances of C
+
Litihum-cell
C
2
1
SDO_TMDO
SDI_TMDI
to C
4
is a 15 nF fixed capacitor used for the
TEST3
CDEM
VSINT
POUT
9
RSSI
SCK
CLK
IRQ
NC
3
CS
2
and C
5
are 68 nF voltage supply blocking
is a feed inductor of about 120 nH.
C
, C
XTAL2
4
6
8
and C
are thus important. The qual-
8
13.25311 MHz
, C
C
VCC
3
Microcontroller
9
are also important.
5
, C
VSS
4829D–RKE–06/06
6
, C
8
and C
9