ATA5757 ATMEL Corporation, ATA5757 Datasheet - Page 8

• Manufacturer Part Number: ATA5757
• Description: (ATA5756 / ATA5757) UHF ASK/FSK TRANSMITTER
• Manufacturer: ATMEL Corporation

Accuracy of Frequency
Deviation
8
ATA5756/ATA5757
Figure 7. Timing ASK Mode with ENABLE Connected to the Microcontroller
The accuracy of the frequency deviation using the XTAL pulling method is about ±20% if
the following tolerances are considered. One important aspect is that the values of C
and C
quency deviation.
Figure 8. Tolerances of Frequency Modulation
Using a crystal with a motional capacitance of C
capacitance of C
C
326 × C
parasites of C
and C
erances of ±15.8 kHz to ±23.2 kHz.
M
ENABLE
results in C
5
M
ASK
FSK
CLK
= 15 pF ±1% for a nominal frequency deviation of ±19.3 kHz with worst case tol-
of typical crystals are strongly correlated which reduces the tolerance of the fre-
M
). If using the internal FSK switch with C
XTAL
Stray
Power-down
0
V
LNOM
= 297 × C
S
~
= 0.7 pF ±10%, the resulting C
= 18 pF and a parallel capacitance of C
M
∆T
(the correlation has a tolerance of 10%, so C
XTO
Power-up,
PA off
Crystal equivalent circuit
C
> 250 µs
M
L
M
C
0
Power-up,
PA on
(High)
R
4
S
Switch
M
and C
= 4.37 fF ±15%, a nominal load
= 0.9 pF ±20% and estimated
Power-up,
5
PA off
values are C
(Low)
C
0
Stray
= 1.30 pF correlated with
C
5
C
Switch
C
4
4
Power-down
4702H–RKE–09/04
= 10 pF ±1%
0
= 267 to
0