Rainbow Electronics ATA5746 - Manual (Page 16)

16
4596A–RKE–05/06
ATA5745/ATA5746 [Preliminary]
Lower values of C
m
can be used, slightly increasing the start-up time. Lower values of C
0
or
higher values of C
m
(up to 15 fF) can also be used, with only little influence on pulling.
Figure 3-2. XTO Block Diagram
The relationship between f
XTO
and the f
RF
is shown in Table 3-1 .
Attention must be paid to the harmonics of the CLK_OUT output signal f
CLK_OUT
as well as to the
harmonics produced by an microprocessor clocked with it, since these harmonics can disturb
the reception of signals if they get to the RF input. If the CLK_OUT signal is used, it must be
carefully laid out on the application PCB. The supply voltage of the microcontroller must also be
carefully blocked.
Table 3-1. Calculation of f
RF
Frequency [MHz] f
XTO
[MHz] f
RF
433.92 (ATA5745) 13.57375 f
XTO
x 32 – 440 kHz
315.0 (ATA5746) 13.1433 f
XTO
x 24 – 440 kHz
C
L2
C
L1
f
DCLK
f
FXTO
CLK_OUT_CTRL1 CLK_OUT_CTRL0
XTO_OK
XTAL1 XTAL2 CLK_OUT
Amplitude
Detector
Divider
/16
&
Divider
/3, /6, /12