ATA8402 ATMEL Corporation, ATA8402 Datasheet - Page 5

• Manufacturer Part Number: ATA8402
• Manufacturer: ATMEL Corporation

4.3
4.3.1
4.3.2
4982A–IND–02/07
CLK Output
Clock Pulse Take-over
Output Matching and Power Setting
Figure 4-1.
Using C
tances on each side of the crystal of C
crystal of C
ation of ±21 kHz with worst case tolerances of ±16.3 kHz to ±28.8 kHz.
An output CLK signal is provided for a connected microcontroller. The delivered signal is CMOS
compatible if the load capacitance is lower than 10 pF.
The clock of the crystal oscillator can be used for clocking the microcontroller. A special feature
of Atmel
with ENABLE = H, and after 1 ms assumes the clock signal of the transmission IC, so that the
message can be sent with crystal accuracy.
The output power is set by the load impedance of the antenna. The maximum output power is
achieved with a load impedance of Z
to V
The delivered current pulse of the power amplifier is 9 mA. The maximum output power is deliv-
ered to a resistive load of 465 if the 1.0 pF output capacitance of the power amplifier is
compensated by the load impedance.
An optimum load impedance of:
Z
7.5 dBm.
The load impedance is defined as the impedance seen from the ATA8402’s ANT1, ANT2 into
the matching network. Do not confuse this large signal load impedance with a small signal input
impedance delivered as input characteristic of RF amplifiers and measured from the application
into the IC instead of from the IC into the application for a power amplifier.
Less output power is achieved by lowering the real parallel part of 465 where the parallel imag-
inary part should be kept constant.
Output power measurement can be done with the circuit shown in
that the component values must be changed to compensate for individual board parasitics until
the ATA8402 has the right load impedance Z
cable used to measure the output power must be calibrated out.
Load
S
= 465 || j/(2
to deliver the DC current.
4
®
= 9.2 pF ±2%, C
’s ATARx9x is that it starts with an integrated RC-oscillator to switch on the ATA8402
0
= 3.2 pF ±10% and a crystal with C
Tolerances of Frequency Modulation
XTAL
V
S
1.0 pF) = (166 + j223) thus results for the maximum output power of
5
= 6.8 pF ±5%, a switch port with C
C
Stray1
Crystal equivalent circuit
Load,opt
C
Stray1
M
= (166 + j223) . There must be a low resistive path
L
= C
C
M
0
Load,opt
Stray2
M
= 13 fF ±10%, typically results in an FSK devi-
R
S
= 1 pF ±10%, a parallel capacitance of the
= (166 + j223) . Also the damping of the
C
Switch
Stray2
C
5
Figure 4-2 on page
= 3 pF ±10%, stray capaci-
C
Switch
C
4
ATA8402
6. Note
5