ATA5423 ATMEL Corporation, ATA5423 Datasheet - Page 28

• Manufacturer Part Number: ATA5423
• Manufacturer: ATMEL Corporation

Table 4-1.
4.1
28
Frequency
433.92
(MHz)
868.3
315
345
915
Pin CLK
ATA5423/25/28/29 [Preliminary]
Calculation of f
433_N868
AVCC
AVCC
AVCC
Pin 6
GND
GND
The variable FREQ depends on FREQ2 and FREQ3, which are defined by the bits FR0 to FR12
in control register 2 and 3, and is calculated as follows:
FREQ = FREQ2 + FREQ3
Care must be taken to the harmonics of the CLK output signal f
produced by an microprocessor clocked with it, since these harmonics can disturb the reception
of signals if they get to the RF input. In a single channel system, using FREQ = 3803 to 4053
ensures that the harmonics of this signal do not disturb the receive mode. In a multichannel sys-
tem, the CLK signal can either be not used or carefully laid out on the application PCB. The
supply voltage of the microcontroller must also be carefully blocked in a multichannel system.
Pin CLK is an output to clock a connected microcontroller. The clock frequency f
as follows:
Because the enabling of pin CLK is asynchronous, the first clock cycle may be incomplete. The
signal at CLK output has a nominal 50% duty cycle.
f
CLK
RF
CREG1
Bit(4)
FS
=
1
0
0
0
0
f
---------- -
XTO
3
f
XTO
12.73193
13.94447
13.25311
13.41191
14.13324
(MHz)
f
f
f
f
f
XTO
XTO
XTO
XTO
XTO
f
RF
24.5
24.5
64.5
64.5
32.5
= f
TX_ASK
+
+
+
+
+
FREQ
--------------------------------- -
FREQ
--------------------------------- -
FREQ
--------------------------------- -
FREQ
--------------------------------- -
FREQ
--------------------------------- -
16384
16384
16384
16384
16384
= f
+
+
+
+
+
RX
20.5
20.5
20.5
20.5
20.5
15.54 kHz
17.02 kHz
16.17 kHz
16.37 kHz
17.25 kHz
f
TX_FSK_L
f
f
f
f
f
RF
RF
RF
RF
RF
–
–
–
–
–
CLK
as well as to the harmonics
15.54 kHz
17.02 kHz
16.17 kHz
16.37 kHz
17.25 kHz
f
TX_FSK_H
f
f
f
f
f
RF
RF
RF
RF
RF
+
+
+
+
+
CLK
4841A–RKE–02/05
is calculated
Resolution
Frequency
777.1 Hz
851.1 Hz
808.9 Hz
818.6 Hz
862.6 Hz