ATA5811-PLQX Atmel, ATA5811-PLQX Datasheet - Page 6

• Manufacturer Part Number: ATA5811-PLQX
• Manufacturer: Atmel

Specifications of ATA5811-PLQX

• Operating Temperature (min): -40C
• Operating Temperature (max): 105C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 7mm
• Product Height (mm): 0.9mm
• Product Length (mm): 7mm
• Lead Free Status / Rohs Status: Compliant

Application Circuits
Figure 4. Typical RKE Key Fob or Sensor Application, 433.92 MHz, 1 Battery
Typical Key Fob or
Sensor Application with
1 Battery
6
ATA5811/ATA5812 [Preliminary]
Loop antenna
C
AVCC
10
L
2
L
1
Figure 4 shows a typical 433.92 MHz RKE key fob or sensor application with one battery
The external components are 11 capacitors, 1 resistor, 2 inductors and a crystal. C
C
tor. C
highpass frequency of the data filter. C
of 1 pF to 33 pF. L1 is a matching inductor of about 5.6 nH to 56 nH. L
tor of about 120 nH. A load capacitor of 9 pF for the crystal is integrated. R
22 k and sets the output power to about 5.5 dBm. The loop antenna’s quality factor is
somewhat reduced by this application due to the quality factor of L
switch. On the other hand, this lower quality factor is necessary to have a robust design
with a bandwidth that is broad enough for production tolerances. Due to the single-
ended and ground-referenced design, the loop antenna can be a free-form wire around
the application as it is usually employed in RKE uni-directional systems. The
ATA5811/ATA5812 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 to relax the tolerance specification of the RF components and to get a high
antenna efficiency in spite of their lower quality factor.
C
4
5
C
are 68 nF voltage supply blocking capacitors. C
C
C
11
8
9
6
R
is a 15 nF fixed capacitor used for the internal quasi peak detector and for the
1
C
433_N868
RF_OUT
NC
NC
NC
RF_IN
NC
NC
R_PWR
PWR_H
NC
NC
7
C
C
2
1
ATA5811/ATA5812
+
Litihum-
Cell
C
4
SDO_TMDO
7
DEM_OUT
SDI_TMDI
N_RESET
to C
CDEM
VSINT
RSSI
SCK
CLK
IRQ
NC
CS
11
C
XTAL2
6
are RF matching capacitors in the range
5
is a 10 nF supply blocking capaci-
Microcontroller
C
VCC
13.25311 MHz
3
VSS
2
2
and the RX/TX
is a feed induc-
4689B–RKE–04/04
1
is typically
1
to