ATAB8402 Atmel, ATAB8402 Datasheet - Page 9

• Manufacturer Part Number: ATAB8402
• Description: BOARD DEMO 433MHZ RF TRANSMITTER
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATAB8402

• Frequency: 433MHz
• Wireless Frequency: 315 MHz
• Modulation: ASK, FSK
• For Use With/related Products: ATA8402
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

9115A–INDCO–01/08
In real applications, there are stray capacitances on the board have to be taken into account
when determining the load capacitance.
If FSK modulation is used, the crystal-loaded resonance frequency is pulled by two different
capacitance values (CL1 and CL2) due to the data.
modulation. The frequency deviation can be estimated using formula 16.
Figure 2-9.
Notes:
When determining C1 and C2, C
switch is open, the C
resistance Re{Z
microprocessor must be taken into account.
Caution: the formulas provide a theoretical start value for tuning of the real values on the appli-
cation board.
lm Z
XTAL
1.
2. C
=
f is the ± frequency deviation in ppm
M
-lm Z
is the motional capacitance of the crystal.
Circuitry for FSK Modulation
XTAL
XTO
}. If the switch is closed, the on resistance of the modulating port of the
switch
–
----------------
f
2 f
L
must be taken into account in the calculation of the series resonance
C
M
XTAL
VS
switch
Z
XTO
Equation 16
of the microprocessor’s pin must be considered. If the
ATA8401/ATA8402/ATA8403
Z
XTAL
XTAL
Figure 2-9
C
C
L1
L2
C
C
1
2
shows the principle circuit for FSK
C
switch
9