TDA5252G2 INFINEON [Infineon Technologies AG], TDA5252G2 Datasheet - Page 50

• Manufacturer Part Number: TDA5252G2
• Description: ASK/FSK 915MHz Wireless Transceiver
• Manufacturer: INFINEON [Infineon Technologies AG]

To set the 3 different frequencies 3 different C
capacitors can be combined to generate the necessary C
Internal banks of switchable capacitors allow the finetuning of these frequencies.
3.2.2
Depending on whether the device operates in transmit or receive mode or whether it operates in
ASK or FSK the following cases can be distinguished:
3.2.2.1
In transmit mode the two frequencies representing logical HIGH and LOW data states have to be
adjusted depending on the intended frequency deviation and separately according to the following
formulas:
f
e.g.
with a frequency deviation of 50kHz.
Figure 3-14 shows the configuration of the switches and the capacitors to achieve the 2 desired
frequencies. Gray parts of the schematics indicate inactive parts. For FSK modulation the ASK-
switch is always open.
For FSK LOW the FSK-switch is closed and C
by:
For finetuning C tune1 can be varied over a range of 8 pF in steps of 125fF. The switches of this C-
bank are controlled by the bits D0 to D5 in the FSK register (subaddress 01H, see Table 3-6).
For FSK HIGH the FSK-switch is open. So the effective C
The C-bank C tune2 can be varied over a range of 16 pF in steps of 250fF for finetuning of the FSK
HIGH frequency. The switches of this C-bank are controlled by the bits D8 to D13 in the FSK
register (subaddress 01H, see Table 3-6).
Data Sheet
COSC HI
C
C
V
v+
−
= (f
f
f
COSC HI
COSC LOW
=
=
RF
C
Transmit/Receive ASK/FSK Frequency Assignment
FSK-mode
(
-------------------------------------------------------------------------------------- -
C v1
C
v
+ f
1
v1
+
DEV
+
+
C
C tune1
C
) / 48
tune
tune1
= (915E6 + 50E3) / 48 = 19,0635167MHz
= (915E6 - 50E3) / 48 = 19,0614583MHz
1
)
+
⋅
(
C
C v2
v2
+
+
C
f
C tune2
COSC LOW
tune2
)
v2
= (f
50
and C
v
RF
are necessary. Via internal switches 3 external
- f
tune2
DEV
v+
) / 48
are bypassed. The effective C
v
is given by:
in case of ASK- or FSK-modulation.
[3 – 20]
[3 – 21]
[3 – 19]
TDA5252 G2
Version 1.1
Application
2007-02-26
v-
is given