ATA5812-PLQW Atmel, ATA5812-PLQW Datasheet - Page 6

• Manufacturer Part Number: ATA5812-PLQW
• Manufacturer: Atmel

Specifications of ATA5812-PLQW

• 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

2. Typical Key Fob or Sensor Application with 1 Battery
Figure 2-1.
6
ATA5811/ATA5812
Typical RKE Key Fob or Sensor Application, 433.92 MHz, 1 Battery
Loop antenna
AVCC
C
10
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 highpass frequency of the data fil-
ter. C
of about 5.6 nH to 56 nH. L
crystal is integrated. R
antenna’s quality factor is somewhat reduced by this application due to the quality factor of L
and the RX/TX 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 suffi-
cient 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.
L
2
L
1
7
C
to C
5
C
C
shows a typical 433.92 MHz RKE key fob or sensor application with one battery The
11
C
8
9
11
are RF matching capacitors in the range of 1 pF to 33 pF. L1 is a matching inductor
R
1
C
7
NC
NC
NC
RF_IN
NC
433_N868
NC
R_PWR
PWR_H
RF_OUT
NC
NC
1
is typically 22 k and sets the output power to about 5.5 dBm. The loop
2
C
C
is a feed inductor of about 120 nH. A load capacitor of 9 pF for the
1
2
ATA5811/ATA5812
+ Lithium cell
5
is a 10 nF supply blocking capacitor. C
C
4
SDO_TMDO
DEM_OUT
SDI_TMDI
N_RESET
CDEM
VSINT
RSSI
SCK
CLK
IRQ
CS
NC
C
13.25311 MHz
6
XTAL2
C
3
Microcontroller
VCC
VSS
6
1
is a 15 nF fixed
to C
4689F–RKE–08/06
4
are 68 nF
2